Using sales from July onwards, due to the abundance of sales here.

Sales 1-8:

Sold for $38.74, $35, $33.99, $28.51, $27.99 (2x), $18.19, and $18.11.

https://marketplace.tf/items/30658;5;u97

https://backpack.tf/item/6260397391 - Julia’s B/O has been consistently 14 ($27.99 sale on 8th August).

https://backpack.tf/item/4224717919 - No B/O

https://backpack.tf/item/4235441497 - No B/O

http://manic.tf/keyprice/?at=2018-07-11 - $38.74 / $1.97 = 19.66 keys

http://manic.tf/keyprice/?at=2018-07-16 - $18.11 / $1.96 = 9.24 keys

http://manic.tf/keyprice/?at=2018-07-17 - $33.99 / $1.95 = 17.43 keys

http://manic.tf/keyprice/?at=2018-08-08 - $27.99 / $1.89 = 14.81 keys, capped at 14

http://manic.tf/keyprice/?at=2018-08-10 - $35 / $1.87 = 18.72 keys

http://manic.tf/keyprice/?at=2018-08-11 - $18.19 / $1.87 = 9.73 keys

http://manic.tf/keyprice/?at=2018-08-19 - $28.51 / $1.9 = 15.01 keys

http://manic.tf/keyprice/?at=2018-08-21 - $27.99 / $1.9 = 14.73 keys

X = 20

X = 19

X = 17

X = 15 (2x)

X = 14 (Capped by B/O)

X = 9.5

X = 9

Sale 9:

Sold for Magnetic Hat Protector Universal Translator (18.5)

No outpost

Seller: https://backpack.tf/profiles/76561198252473132#!/compare/1527984000/1531526400

Buyer: https://backpack.tf/profiles/76561198372104728#!/compare/1531526400/1532995200 - no useful compare link available

https://backpack.tf/item/6931467518

X = 19

Sale 10:

Sold with 4 keys for Subatomic Universal Translator (18)

Seller: https://backpack.tf/profiles/76561198411062990#!/compare/1533168000/1533340800

Buyer: https://backpack.tf/profiles/76561198334598690#!/compare/1533254400/1533340800

https://backpack.tf/item/6849765616

X = 14

Sale 11:

Sold for 14 keys

Seller: https://backpack.tf/profiles/76561198312583107#!/compare/1530835200/1530921600

Buyer: https://backpack.tf/profiles/76561198212675672#!/compare/1530748800/1530921600

https://backpack.tf/item/6774782870

X = 14

Sale 12:

Sold for 14 keys

Seller: https://backpack.tf/profiles/76561198080179568#!/compare/1531267200/1531353600

Buyer: https://backpack.tf/profiles/76561198035743299#!/compare/1531353600/1533427200

https://backpack.tf/item/6774782870

X = 14

Sale 13:

Sold for 14 keys

Seller: https://backpack.tf/profiles/76561198024867201#!/compare/1535760000/1535846400

Buyer: https://backpack.tf/profiles/76561198206290207#!/compare/1535846400/1535932800

https://backpack.tf/item/6712294003

X = 14

Sale 14:

Sold for Electric Hat Protector Universal Translator (14.5) + giftapult

http://www.tf2outpost.com/trade/29732494 - B/O of 14

Seller: https://backpack.tf/profiles/76561198080179568#!/compare/1533427200/1533513600

Buyer: https://backpack.tf/profiles/76561198349207524#!/compare/1533427200/1533513600

https://backpack.tf/item/4246025213

X = 14 (Capped by B/O)

Sale 15:

Sold for Terror-Watt Titanium Tyrolean (14)

No outpost

Seller: https://backpack.tf/profiles/76561198349207524#!/compare/1533513600/1533772800

Buyer: https://backpack.tf/profiles/76561198281546993#!/compare/1533686400/1533772800

X = 14

Sale 16:

Sold for 14 keys

Seller: https://backpack.tf/profiles/76561198832602199#!/compare/1533513600/1533686400

Buyer: https://backpack.tf/profiles/76561198024798544#!/compare/1533513600/1533600000

https://backpack.tf/item/4235441497

https://i.imgur.com/tARHRkJ.png

X = 14

Sale 17:

Sold for 14 keys + 14 ref

Seller: https://backpack.tf/profiles/76561198312583107#!/compare/1532304000/1532390400

Buyer: https://backpack.tf/profiles/76561198132329942#!/compare/1532304000/1532390400

https://backpack.tf/item/6920312961

https://i.imgur.com/tARHRkJ.png

X = 14

Sale 18:

Bought from scrap.tf for 12 keys + ~1 key in metal

Seller: https://backpack.tf/profiles/76561198135388328#!/compare/1534636800/1534723200

Buyer: https://backpack.tf/profiles/76561198038272717#!/compare/1534636800/1534723200

https://backpack.tf/item/6947951779

X = 13

Sale 19:

Sold for 13 keys

Seller: https://backpack.tf/profiles/76561198805549376#!/compare/1533945600/1534032000

Buyer: https://backpack.tf/profiles/76561198160644852#!/compare/1534032000/1534118400

https://backpack.tf/item/4246025213

X = 13

Sale 20:

Quicksold for 12 keys + less than half a key in metal

Seller: https://backpack.tf/profiles/76561198281546993#!/compare/1533772800/1533859200

Buyer: https://backpack.tf/profiles/76561198805549376#!/compare/1533772800/1533859200

https://backpack.tf/item/4246025213

X = 12

Sale 21:

Sold to a bot for 12 keys + 6.33 ref

Seller: https://backpack.tf/profiles/76561198184012267#!/compare/1531958400/1532131200

Buyer: https://backpack.tf/profiles/76561198357046243#!/compare/1531872000/1531958400

https://backpack.tf/item/4609502188

https://i.imgur.com/tARHRkJ.png

X = 12

Other Sales:

https://backpack.tf/item/7042547953 (#1 & #2, rest were untraceable/tradebacks)

https://backpack.tf/item/7008266434 (#3 & #4)

https://backpack.tf/item/7003687630 (#5 & #6)

https://backpack.tf/item/6947951779 (#7-9)

https://backpack.tf/item/6774782870 (#10-12)

https://backpack.tf/item/6768856158 (#13)

https://backpack.tf/item/6260397391 (#14 & #15)

https://backpack.tf/item/4609502188 (#16 & 17)

https://backpack.tf/item/4315989099 (#18 & 19)

https://backpack.tf/item/4301412278 (#20 & #21)

https://backpack.tf/item/4274574711 (#22, the rest were gambled)

https://backpack.tf/item/4246025213 (#23)

https://backpack.tf/item/4235441497 (#24-28)

https://backpack.tf/item/6920312961 (#29 & 30, rest are mannco.trade/tf2mart stuff)

https://backpack.tf/item/4339034876 - Scammer

#1

Untraceable, sold to scrap.tf

https://backpack.tf/profiles/76561197964546925#!/compare/1534118400/1534204800

https://backpack.tf/profiles/76561198135388328#!/compare/1534118400/1534204800

11 keys and some metal match, but I’m certain it sold for more than that.

#2

Untraceable, bought from scrap.tf

https://backpack.tf/profiles/76561198135388328#!/compare/1534118400/1534204800

https://backpack.tf/profiles/76561198136810568#!/compare/1531612800/1534982400

#3

Untraceable

https://backpack.tf/profiles/76561198406757086#!/compare/1535155200/1535673600

https://backpack.tf/profiles/76561198166027474#!/compare/1528329600/1535760000

#4

Untraceable

https://backpack.tf/profiles/76561198216531363#!/compare/1532131200/1533427200

https://backpack.tf/profiles/76561198342161127#!/compare/1533254400/1533340800

#5

Sold for Dead Presidents Your Worst Nightmare

https://backpack.tf/profiles/76561198047941585#!/compare/1532736000/1532822400

https://backpack.tf/profiles/76561198115686239#!/compare/1532476800/1533168000

Better to use on the YWN

#6

Bulk for Beams Larrikin

https://backpack.tf/profiles/76561198115686239#!/compare/1533859200/1533945600

https://backpack.tf/profiles/76561198335791307#!/compare/1533772800/1533859200

#7

Untraceable

https://backpack.tf/profiles/76561198418421695#!/compare/1534118400/1535414400

https://backpack.tf/profiles/76561198407426968#!/compare/1534204800/1534291200

Only the cheap cosmetics match.

#8

Sold for a bunch of items, mostly taunts.

https://backpack.tf/profiles/76561198407426968#!/compare/1534377600/1534464000

https://backpack.tf/profiles/76561198130609277#!/compare/1534291200/1534464000

Better to not use a sale like this.

#9

Untraceable, sold to scrap.tf

https://backpack.tf/profiles/76561198130609277#!/compare/1534464000/1534636800

https://backpack.tf/profiles/76561198135388328#!/compare/1534377600/1534464000

#10

Untraceable

https://backpack.tf/profiles/76561198312583107#!/compare/1530403200/1530489600

https://backpack.tf/profiles/76561198146470794#!/compare/1528588800/1530489600

https://i.imgur.com/tARHRkJ.png - Labelled as a 14 key sale

#11

Untraceable

https://backpack.tf/profiles/76561198146470794#!/compare/1530489600/1530921600

https://backpack.tf/profiles/76561198312583107#!/compare/1530403200/1530489600

https://i.imgur.com/tARHRkJ.png - Labelled as a 12 key + 6 ref purchase

#12

Most likely sold for keys

https://backpack.tf/profiles/76561198212675672#!/compare/1530921600/1531008000

https://backpack.tf/profiles/76561198080179568#!/compare/1530835200/1530921600

#13

Untraceable, probably transferred between accounts

https://backpack.tf/profiles/76561198093903290#!/compare/1534377600/1534982400

https://backpack.tf/profiles/76561198850159161

#14

Untraceable, most likely went to a buy order

https://backpack.tf/profiles/76561198036445124#!/compare/1533254400/1533340800

https://backpack.tf/profiles/76561198080179568#!/compare/1533254400/1533340800

#15

Untraceable

https://backpack.tf/profiles/76561198098142914#!/compare/1516752000/1530921600

https://backpack.tf/profiles/76561198342161127#!/compare/1530835200/1530921600

#16

Untraceable

https://backpack.tf/profiles/76561198311498888#!/compare/1531699200/1531785600

https://backpack.tf/profiles/76561198184012267#!/compare/1531785600/1531958400

#17

Untraceable

https://backpack.tf/profiles/76561198358556666#!/compare/1535155200/1535241600

https://backpack.tf/profiles/76561198354299484#!/compare/1515456000/1535241600

https://i.imgur.com/tARHRkJ.png - Labelled as a 13 key + 29 ref sale, only 7 keys match here.

#18

Untraceable, sold to scrap.tf

https://backpack.tf/profiles/76561198375319999#!/compare/1531872000/1531958400

https://backpack.tf/profiles/76561198135388328#!/compare/1531872000/1531958400

#19

Untraceable, bought from scrap.tf

https://backpack.tf/profiles/76561198135388328#!/compare/1531872000/1531958400

https://backpack.tf/profiles/76561198352564932#!/compare/1531353600/1533340800

#20

Untraceable

https://backpack.tf/profiles/76561198311498888#!/compare/1532736000/1532822400

https://backpack.tf/profiles/76561198353947264#!/compare/1532476800/1533513600

#21

Untraceable, sold to a quickbuyer

https://backpack.tf/profiles/76561198353947264#!/compare/1533600000/1534032000

https://backpack.tf/profiles/76561198080179568#!/compare/1533513600/1533600000

#22

Untraceable, sold to scrap.tf

https://backpack.tf/profiles/76561198126155258#!/compare/1534377600/1534464000

https://backpack.tf/profiles/76561198135388328#!/compare/1534377600/1534464000

#23

Sold with ~1 key in items for Nuts Tin Capotain + Planets Head Hedge

https://backpack.tf/profiles/76561198160644852#!/compare/1534809600/1534982400

https://backpack.tf/profiles/76561198412364405#!/compare/1534896000/1534982400

Gonna be way too high without a B/O, excluding.

#24

Untraceable, sold to scrap.tf

https://backpack.tf/profiles/76561198169991309#!/compare/1531267200/1536105600

https://backpack.tf/profiles/76561198135388328#!/compare/1532908800/1532995200

#25

Untraceable, bought from scrap.tf

https://backpack.tf/profiles/76561198135388328#!/compare/1532908800/1532995200

https://backpack.tf/profiles/76561198098536989#!/compare/1532908800/1532995200

#26

Sold for Purple Confetti Slope Scopers + some metal

https://backpack.tf/profiles/76561198098536989#!/compare/1532995200/1533081600

https://backpack.tf/profiles/76561198418244311#!/compare/1532995200/1533081600

Better to use the sale on the Slope Scopers, though if the Stormy Steel Toe wasn’t involved, I’m sure something else was.

#27

Untraceable

https://backpack.tf/profiles/76561198418244311#!/compare/1532995200/1533081600

https://backpack.tf/profiles/76561198126114757#!/compare/1532908800/1533081600

#28

Untraceable

https://backpack.tf/profiles/76561198024798544#!/compare/1533686400/1533945600

https://backpack.tf/profiles/76561198378451439#!/compare/1533859200/1534032000

#29

Untraceable

https://backpack.tf/profiles/76561198257658390#!/compare/1530316800/1532304000

https://backpack.tf/profiles/76561198312583107#!/compare/1532217600/1532304000

https://i.imgur.com/tARHRkJ.png - Labelled as a 12 key + 6 ref purchase

#30

Untraceable

https://backpack.tf/profiles/76561198132329942#!/compare/1532476800/1532736000

https://backpack.tf/profiles/76561198342161127#!/compare/1532649600/1532736000

Sellers:

https://i.imgur.com/n8zLQ4p.png

https://backpack.tf/item/7003687630 - ~13.87 keys

https://backpack.tf/item/4301412278 - 14 keys

https://backpack.tf/item/6947951779 - 15 keys

Sales at:

9

9.5

12 (2x)

13 (2x)

14 (9x)

15 (2x)

17

19 (2x)

20

The two sellers near 14 going nearly a month unsold shows that anything higher would be too high. Excluding 15+.

Buyers at ~11.6 keys, 9 and 9.5 are obvious outliers. Excluding 9 and 9.5.

At the moment, there is nothing countering the sales at 12, other than the fact that they went to quickbuyers. Bot.tf indicates that there are also a lot of purchases at ~12 keys (one of them being invalid, as it was bulk). Therefore, I’ll be keeping 12 in the range.

Going with 12-14.