Sale 1: Untrace.

https://backpack.tf/profiles/76561198444060701#!/compare/1555027200/1555113600

https://backpack.tf/profiles/76561198277409359#!/compare/1555027200/1555113600

Sale 2: ~12 Keys Pure.

https://backpack.tf/profiles/76561198277409359#!/compare/1555977600/1556064000

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

Sale 3: Untrace.

https://backpack.tf/profiles/76561198139969353#!/compare/1556150400/1556236800

https://backpack.tf/profiles/76561198327837250#!/compare/1556150400/1556236800

Sale 4: ~13 Keys Pure.

https://backpack.tf/profiles/76561198327837250#!/compare/1556236800/1556323200

https://backpack.tf/profiles/76561198131551260#!/compare/1556236800/1556323200

Sale 5: ~12 Keys Pure.

https://backpack.tf/profiles/76561198131551260#!/compare/1556323200/1556841600

https://backpack.tf/profiles/76561198083826540#!/compare/1556755200/1556841600

Sale 6: Untrace.

https://backpack.tf/profiles/76561198083826540#!/compare/1556755200/1556841600

https://backpack.tf/profiles/76561198240537922#!/compare/1556755200/1556841600

Sale 7: Untrace.

https://backpack.tf/profiles/76561198240537922#!/compare/1556755200/1556841600

https://backpack.tf/profiles/76561198081793950#!/compare/1556755200/1556841600

Sale 8: Untrace.

https://backpack.tf/profiles/76561198081793950#!/compare/1556841600/1556928000

https://backpack.tf/profiles/76561198043840980#!/compare/1556841600/1556928000

Sale 9: Untrace.

https://backpack.tf/profiles/76561198043840980#!/compare/1556841600/1556928000

https://backpack.tf/profiles/76561198080179568#!/compare/1556841600/1556928000

Sale 10: Bulk.

https://backpack.tf/profiles/76561198271964074#!/compare/1559606400/1559692800

https://backpack.tf/profiles/76561198280357510#!/compare/1559606400/1559692800

Sale 11: ~12 Keys.

https://backpack.tf/profiles/76561198280357510#!/compare/1559606400/1559692800

https://backpack.tf/profiles/76561198140348221#!/compare/1559606400/1559692800

Sale 12: Untrace/Low.

https://backpack.tf/profiles/76561198140348221#!/compare/1559606400/1559692800

https://backpack.tf/profiles/76561198302841269#!/compare/1559606400/1559692800

Sale 13: Untrace/Low.

https://backpack.tf/profiles/76561198302841269#!/compare/1559606400/1559692800

https://backpack.tf/profiles/76561198093662059#!/compare/1559520000/1559692800

Sale 14: ~11 Keys Pure.

https://backpack.tf/profiles/76561198093662059#!/compare/1559520000/1559692800

https://backpack.tf/profiles/76561198002757046#!/compare/1559606400/1559692800

Sale 15: ~11 Keys.

Sold With 3 keys for Circling Peace Sign Vampire Vanquisher (13.5) = 10.5 keys.

https://backpack.tf/profiles/76561198028171245#!/compare/1560124800/1560470400

https://backpack.tf/profiles/76561197964171516#!/compare/1560124800/1560211200

Sale 16: Untrace.

https://backpack.tf/profiles/76561198305494036#!/compare/1553990400/1554076800

https://backpack.tf/profiles/76561198044717076#!/compare/1551398400/1554336000

https://backpack.tf/item/6995834571 - Trade Back.

Sales: 11/11/12/12/12/13

Going with 11-13 keys. - Thanks to foamy.

Thanks to scourge for the premium!