Sale 1:

https://backpack.tf/profiles/76561198348738792#!/compare/1550793600/1550966400

https://backpack.tf/profiles/76561198350879574#!/compare/1550707200/1550793600

https://backpack.tf/profiles/76561198248296912#!/compare/1550707200/1550793600

https://backpack.tf/profiles/76561198838870134#!/compare/1550707200/1550793600

Untrace

Sale 2:

https://backpack.tf/profiles/76561198838870134#!/compare/1551052800/1551139200

https://backpack.tf/profiles/76561198363395191#!/compare/1551052800/1551139200

QS to bot

Sale 3:

https://backpack.tf/profiles/76561198262993846#!/compare/1552003200/1552089600

https://backpack.tf/profiles/76561198363395191#!/compare/1552003200/1552089600

QS to bot

sale 4:

https://backpack.tf/profiles/76561198098142540#!/compare/1552435200/1553558400

https://backpack.tf/profiles/76561198093031738#!/compare/1552867200/1552953600

Untrace

Sale 5:

https://backpack.tf/profiles/76561198337734785#!/compare/1554076800/1554163200

https://backpack.tf/profiles/76561198215818307#!/compare/1548979200/1554163200

Tradeback

Sale 6:

https://backpack.tf/profiles/76561198337734785#!/compare/1555200000/1555286400

https://backpack.tf/profiles/76561198065282605#!/compare/1555286400/1555372800

Sold for 11 keys

Sale 7:

https://backpack.tf/profiles/76561198065282605#!/compare/1555977600/1556064000

https://backpack.tf/profiles/76561198345730410#!/compare/1555977600/1556064000

Untrace

Sale 8:

https://backpack.tf/profiles/76561198345730410#!/compare/1555977600/1556064000

https://backpack.tf/profiles/76561198139969353#!/compare/1555977600/1556064000

Sold for 10 keys

Sale 9:

https://backpack.tf/profiles/76561198139969353#!/compare/1555977600/1556064000

https://backpack.tf/profiles/76561198302399911#!/compare/1555977600/1556064000

Sold with negligible sweets for 10 keys

Sale 10:

https://backpack.tf/profiles/76561198302399911#!/compare/1556064000/1556150400

https://backpack.tf/profiles/76561198167885639#!/compare/1556064000/1556150400

Sold with 2 keys for Planets Runner(13)

Total is 11 keys

Sale 11:

https://backpack.tf/profiles/76561198167885639#!/compare/1556150400/1556236800

https://backpack.tf/profiles/76561198850003204#!/compare/1556064000/1556236800

Sold with negligible sweets for C9 Letch's

Use there

Sale 12:

https://marketplace.tf/items/602;5;u57

$19.99 / $1.8 = 11.11 keys

Total sales @:

10, 10, 11, 11, 11.11 keys

Taking 10 - 11 keys.