Didn't think there would be so many..

SALE 1

sold for 11 keys

https://backpack.tf/profiles/76561198126159778#!/compare/1563408000/1563580800

https://backpack.tf/profiles/76561198297554259#!/compare/1563321600/1563494400

SALE 2

sold with stormy pe and sweets for keys

https://backpack.tf/profiles/76561198375014774#!/compare/1556064000/1556150400

https://backpack.tf/profiles/76561198093707809#!/compare/1556064000/1556150400

not using obviously.

SALE 3

sold for steaming gatsby

https://backpack.tf/profiles/76561198093707809#!/compare/1556150400/1556928000

gatsby is outdated @ 4 months, using there as fewer sales for the gatsby.

SALE 4

unknown

https://backpack.tf/profiles/76561198093707809#!/compare/1556150400/1556928000

SALE 5

sold for 11 keys + 7 refined

https://backpack.tf/profiles/76561198101593760#!/compare/1557964800/1558051200

would round down to 11 keys

SALE 6

unknown

https://backpack.tf/profiles/76561198101593760#!/compare/1557964800/1558051200

https://backpack.tf/profiles/76561198928347702#!/compare/1560556800/1560643200

SALE 7

unknown

https://backpack.tf/profiles/76561198173381547#!/compare/1561593600/1561680000

https://backpack.tf/profiles/76561198380840857#!/compare/1561593600/1561680000

SALE 8

sold for 12 keys

https://backpack.tf/profiles/76561198170735867#!/compare/1556668800/1556841600

https://backpack.tf/profiles/76561198125109310#!/compare/1556668800/1556841600

SALE 9

sold for haunted ghosts airdog

https://backpack.tf/profiles/76561198243211546#!/compare/1563148800/1563235200

airdog is indate.

15.5 rounding to 16 keys

b/o was 13.

https://bot.tf/stats/listings/MVVO5JEM

SALE 10

sold for 11 keys + 13 refined + the danger

https://backpack.tf/profiles/76561198453530349#!/compare/1562198400/1562284800

would round down to 11 keys

SALE 11

sold for 12 keys

https://backpack.tf/profiles/76561198014222399#!/compare/1557187200/1557273600

https://backpack.tf/profiles/76561198043992035#!/compare/1557100800/1557273600

SALE 12

sold for 13 keys

https://backpack.tf/profiles/76561198114924746#!/compare/1562112000/1562198400

https://backpack.tf/profiles/76561198928347702#!/compare/1562025600/1562112000

histories of the keys in first compare match up.

b/o was also 13.

https://bot.tf/stats/listings/Y5X69174

SALE 13

sold for aces high cloud crasher

https://backpack.tf/profiles/76561198114924746#!/compare/1562112000/1562198400

cloud crasher outdated @ 2 years, using this sale there as it has fewer sales, or actually nevermind, the buyers there suggest this sale is too low.

SALE 14

sold for 13 keys

https://backpack.tf/profiles/76561198240596970#!/compare/1562112000/1562198400

https://backpack.tf/profiles/76561198838470364#!/compare/1562112000/1562198400

SALE 15

unknown

https://backpack.tf/profiles/76561198014600788#!/compare/1557100800/1557273600

https://backpack.tf/profiles/76561198078900816#!/compare/1556928000/1557532800

SALE 16

bulk for peace sign phantom

https://backpack.tf/profiles/76561197994697258#!/compare/1559174400/1559260800

https://backpack.tf/profiles/76561198144111675#!/compare/1559260800/1559347200

SALE 17

sold for massed flies universal translator + 72' taunt: bad pipes

https://backpack.tf/profiles/76561197964171516#!/compare/1561766400/1561852800

https://backpack.tf/profiles/76561198443489337#!/compare/1561766400/1561852800

both outdated.

b/o was 13.

https://bot.tf/stats/listings/4P880G04

SALE 18

sold for strange professional ks australium axtinguisher + strange professional ks festive flare gun

https://backpack.tf/profiles/76561198443489337#!/compare/1561766400/1561852800

6.3 + 2.89 = 9.19 rounding to 9 keys

SALE 19

sold for 9 keys

https://backpack.tf/profiles/76561198312583107#!/compare/1556409600/1556496000

SALE 20

unknown

https://backpack.tf/profiles/76561198243089884#!/compare/1559088000/1559692800

https://backpack.tf/profiles/76561198038251790#!/compare/1559260800/1559347200

SALE 21

sold for 11 keys

https://backpack.tf/profiles/76561198038251790#!/compare/1559260800/1559347200

https://backpack.tf/profiles/76561198341171690#!/compare/1559260800/1559347200

SALE 22

scm

https://backpack.tf/profiles/76561198216410464#!/compare/1559433600/1561507200

SALE 23

sold with 2.5 keys of sweets for strange festivized specialized ks australium stickybomb launcher

https://backpack.tf/profiles/76561198387582886#!/compare/1562889600/1563062400

https://backpack.tf/profiles/76561198257977681#!/compare/1562889600/1563062400

13.76 - 2.5 = 11.26 rounding to 11 keys

SALE 24

sold with dp bombers bucket hat for tw chieftains + sweets

https://backpack.tf/profiles/76561198387582886#!/compare/1562803200/1562889600

https://backpack.tf/profiles/76561198140559064#!/compare/1562803200/1562889600

better used for chieftains

SALE 25

sold with dp yellow belt for af katyusha

https://backpack.tf/profiles/76561198093418155#!/compare/1563494400/1563580800

better used for katyusha

SALE 26

sold for c9 janissary

https://backpack.tf/profiles/76561198336034192#!/compare/1556323200/1556409600

janisarry outdated @ 2 years, using this there as janissary has fewer sales.

7 sales on marketplace

26.14 on april 29 (26.14 / 1.82 = 14.36 rounding to 14 keys)

28 on may 11 (28 / 1.79 = 15.64 rounding to 16 keys)

28.65 on may 14 (28.65 / 1.8 = 15.9 rounding to 16 keys)

28 on june 1 (28 / 1.82 = 15.38 rounding to 15 keys)

27.4 on june 4 (27.4 / 1.81 = 15.13 rounding to 15 keys)

27.46 on june 23 (27.46 / 1.83 = 15.005 rounding to 15 keys)

27.74 on july 4 (27.74 / 1.84 = 15.07 rounding to 15 keys)

https://marketplace.tf/items/tf2/31010;5;u121

classifieds at the time of making this suggestion.

https://gyazo.com/07489c7890024688f89b0fed8107f4a4

sales at 9, 9, 11, 11, 11, 11, 11, 12, 12, 13, 13, and 13. marketplace sales at 14, 15, 15, 15, 15, 16, and 16. 9 is obviously low due to multiple buyers at 10. going to exclude 16 as well due to so many sales at lower, as well as multiple sellers at lower. taking a range of 11-15 keys here.