Mini for another suggestion :P

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Sale #1 - Untrace

https://backpack.tf/profiles/76561198270038678#!/compare/1559174400/1559347200

https://backpack.tf/profiles/76561198337734785#!/compare/1559260800/1559347200

Sale #2 - 1 for 1 with an orb fire mongolian (Use there)

https://backpack.tf/profiles/76561198010332638#!/compare/1564963200/1565481600

https://backpack.tf/profiles/76561198341171690#!/compare/1565222400/1565308800

Sale #3 - 1 for 1 with 4 key taunt?

https://backpack.tf/profiles/76561198095902384#!/compare/1559952000/1560124800

https://backpack.tf/profiles/76561198230995084#!/compare/1560038400/1560124800

Sale #4 - Untrace

https://backpack.tf/profiles/76561198230995084#!/compare/1560211200/1560297600

https://backpack.tf/profiles/76561198859721638#!/compare/1560211200/1560297600

Sale #5 - 7 keys 26.11 ref

https://backpack.tf/profiles/76561198859721638#!/compare/1560729600/1560816000

https://backpack.tf/profiles/76561198307532189#!/compare/1560729600/1560816000

Sale #6 - Sold with 10 ref for 8 keys

https://backpack.tf/profiles/76561198307532189#!/compare/1562371200/1562457600

https://backpack.tf/profiles/76561198376331369#!/compare/1562371200/1562457600

Sale #7 - Sold with 20 ref sweet for a pro ks ausi blut

https://backpack.tf/profiles/76561198376331369#!/compare/1563062400/1563321600

https://backpack.tf/profiles/76561198451325132#!/compare/1563148800/1563235200

Taking 7 - 0.46 = 6.54 keys

Sale #8 - Bulk

https://backpack.tf/profiles/76561198451325132#!/compare/1564185600/1564358400

https://backpack.tf/profiles/76561198411578160#!/compare/1564185600/1564358400

Sale #9 - Bulk

https://backpack.tf/profiles/76561198345788867#!/compare/1564272000/1564358400

https://backpack.tf/profiles/76561198411578160#!/compare/1564272000/1564358400

Sale #10 - Untrace

https://backpack.tf/profiles/76561198345788867#!/compare/1564358400/1564444800

https://backpack.tf/profiles/76561198401777889#!/compare/1563148800/1564444800

Sale #11 - sold with 25 ref in mixed adds for a Subatomic hfoha (use there)

https://backpack.tf/profiles/76561198317903441#!/compare/1564617600/1564704000

https://backpack.tf/profiles/76561198401777889#!/compare/1564617600/1564704000

Sale #12 - 7 keys 6 ref

https://backpack.tf/profiles/76561198252999692#!/compare/1565654400/1565740800

https://backpack.tf/profiles/76561198074971373#!/compare/1565740800/1565827200

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Taking 7 - 8 keys

Excluding 6.5 keys due to possibly being low