Sale 1:

Sold for 15 keys

Seller: https://backpack.tf/profiles/76561198850003204#!/compare/1563408000/1563580800

Buyer: https://backpack.tf/profiles/76561198117862182#!/compare/1563494400/1563580800

https://backpack.tf/item/606173394

X = 15

Sale 2:

Sold for 13 keys

Seller: https://backpack.tf/profiles/76561198047531524#!/compare/1566086400/1566432000

Buyer: https://backpack.tf/profiles/76561198961513029#!/compare/1566172800/1566259200

https://backpack.tf/item/1343608553

X = 13

Sale 3:

Sold for 13 keys

Seller: https://backpack.tf/profiles/76561198267189538#!/compare/1561852800/1561939200

Buyer: https://backpack.tf/profiles/76561198141559134#!/compare/1561852800/1562112000

https://backpack.tf/item/606173394

X = 13

Sale 4:

Sold for 13 keys

Seller: https://backpack.tf/profiles/76561198006544512#!/compare/1566000000/1566086400

Buyer: https://backpack.tf/profiles/76561198435516344#!/compare/1566000000/1566172800

https://backpack.tf/item/606173394

X = 13

Sale 5:

Sold for 12 keys

Seller: https://backpack.tf/profiles/76561198304343915#!/compare/1567987200/1568073600

Buyer: https://backpack.tf/profiles/76561198026012936#!/compare/1567987200/1568073600

https://backpack.tf/item/7942082016

X = 12

Sale 6:

Sold for 10 keys + 24 ref

Seller: https://backpack.tf/profiles/76561198417413362#!/compare/1565740800/1565827200

Buyer: https://backpack.tf/profiles/76561198047531524#!/compare/1564358400/1565827200

https://backpack.tf/item/1343608553

X = 10

Sale 7:

Sold with 3 keys for Stormy Noble Nickel + some ref

Seller: https://backpack.tf/profiles/76561198026012936#!/compare/1568073600/1568246400

Buyer: https://backpack.tf/profiles/76561198131081286#!/compare/1567987200/1568246400

https://backpack.tf/item/7942082016

Probably better to use on the Nickel. We have enough pure sales and this sale favours the nickel.

Sale 8:

Sold with 2 keys + some ref for Orbiting Fire Backwards Ballcap

Seller: https://backpack.tf/profiles/76561198131081286#!/compare/1568505600/1568592000

Buyer: https://backpack.tf/profiles/76561198006097890#!/compare/1568419200/1568592000

https://backpack.tf/item/7942082016

https://bot.tf/stats/listings/Y9G78RVW - B/O of 16

Same as the last sale, better to use on the Ballcap.

Other Sales:

https://backpack.tf/item/7942082016 (#1-4)

https://backpack.tf/item/606173394 (#5 & #6)

https://backpack.tf/item/5760507188 - mannco

#1

Untraceable

https://backpack.tf/profiles/76561198210550733#!/compare/1563840000/1563926400

https://backpack.tf/profiles/76561198345163634#!/compare/1564185600/1564185600 - no good compare

#2

Sold for Cloud 9 Titanium

https://backpack.tf/profiles/76561197964171516#!/compare/1567209600/1567296000

https://backpack.tf/profiles/76561198173153699#!/compare/1567296000/1567382400

Using on titanium

#3

Untraceable

https://backpack.tf/profiles/76561198173153699#!/compare/1567900800/1567987200

https://backpack.tf/profiles/76561198051504085#!/compare/1567814400/1567900800

#4

Bulk for Cloud 9 HKC

https://backpack.tf/profiles/76561198051504085#!/compare/1567814400/1567900800

https://backpack.tf/profiles/76561198304343915#!/compare/1567814400/1567900800

#5

Bulk for Blizz Muffs

https://backpack.tf/profiles/76561198141559134#!/compare/1562371200/1562457600

https://backpack.tf/profiles/76561198850003204#!/compare/1562371200/1562457600

#6

Untraceable, probably went to a buy order

https://backpack.tf/profiles/76561198117862182#!/compare/1563753600/1563926400

https://backpack.tf/profiles/76561198006544512#!/compare/1563840000/1563926400

Sellers:

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

https://backpack.tf/item/3060322765 - 15 keys, owned for a couple months

Sales at:

10

12

13 (3x)

15

https://bot.tf/stats/listings/4W6Q0EKZ - buy orders were ~10 keys at the time of the ~10 key sale, excluding 10.

Going with 12-15.