Sale 1:

Sold for 10 keys (ID’s match)

Seller: https://backpack.tf/profiles/76561198144795496#!/compare/1515024000/1515196800

Buyer: https://backpack.tf/profiles/76561198025544602#!/compare/1515110400/1515196800

X = 10

Sale 2:

Sold for $19.99 on Marketplace.tf

https://i.imgur.com/C3zS3xG.png - B/O of 9, credit to Bird

https://marketplace.tf/items/1116;5;u3008

https://backpack.tf/item/4272547066

19.99/1.9 = ~10.52

X = 9 (Capped by B/O)

Sale 3:

Sold for Nuts n’ Bolts Sober Stuntman (Mini at 8 below)

Seller: https://backpack.tf/profiles/76561198412458800#!/compare/1516320000/1516406400

Buyer: https://backpack.tf/profiles/76561198236788328#!/compare/1516233600/1516406400

X = 8

Sale 4:

Sold for 7 keys + 2 ref to a quickbuyer

Seller: https://backpack.tf/profiles/76561198025544602#!/compare/1515456000/1515542400

Buyer: https://backpack.tf/profiles/76561198153043737#!/compare/1515542400/1515628800

X = 7

Sale 5:

Bulk for Stormy Desert Marauder

Seller: https://backpack.tf/profiles/76561198236788328#!/compare/1516406400/1516579200

Buyer: https://backpack.tf/profiles/76561198106213567#!/compare/1516492800/1516665600

Nuts Stuntman:

Sale 1:

Sold for 8 keys + 5.11 ref

Seller: https://backpack.tf/profiles/76561198358965606#!/compare/1516233600/1516320000

Buyer: https://backpack.tf/profiles/76561198248807152#!/compare/1516320000/1516406400

X = 8

Sale 2:

Sold for 8 keys

Seller: https://backpack.tf/profiles/76561198271670087#!/compare/1516060800/1516147200

Buyer: https://backpack.tf/profiles/76561198415525729#!/compare/1516060800/1516147200

X = 8

Couldn’t find sales that went over 8.5 keys.

Sellers:

9 keys:

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

https://backpack.tf/item/3891194952

9.6 keys:

https://i.imgur.com/uIjcrCv.png - 22 days

https://backpack.tf/item/5315409584

10 keys:

https://i.imgur.com/ycFec2W.png

https://backpack.tf/item/2892483363

11 keys:

http://www.tf2outpost.com/trade/29528844

Sales at:

7

8

9

10

Quickbuyers at 7, excluding 7.

Going with 8-10.