Sale 1: Untrace.

https://backpack.tf/profiles/76561198107393726#!/compare/1553212800/1553299200

https://backpack.tf/profiles/76561198119634686#!/compare/1553212800/1553299200

Sale 2: Use There.

Sold With 1 key in items for Orbiting Fire Tundra Top.

https://backpack.tf/profiles/76561198394965271#!/compare/1553731200/1553817600

https://backpack.tf/profiles/76561198217390399#!/compare/1553731200/1553817600

Sale 3: Untrace.

https://backpack.tf/profiles/76561198217390399#!/compare/1553817600/1553904000

https://backpack.tf/profiles/76561198090500318#!/compare/1553817600/1553904000

Sale 4: Untrace.

https://backpack.tf/profiles/76561198090500318#!/compare/1553990400/1554163200

https://backpack.tf/profiles/76561198230105584#!/compare/1554076800/1554249600

Sale 5: all key histories match, 15k

https://backpack.tf/profiles/76561198230105584#!/compare/1554076800/1554249600

https://backpack.tf/profiles/76561198823992731#!/compare/1554163200/1554249600

Sale 6: Untrace.

https://backpack.tf/profiles/76561198823992731#!/compare/1555545600/1555632000

https://backpack.tf/profiles/76561198006544512#!/compare/1555545600/1555632000

Sale 7: ~16 Keys Pure.

https://backpack.tf/profiles/76561198006544512#!/compare/1556582400/1556668800

https://backpack.tf/profiles/76561198063150517#!/compare/1556582400/1556668800

Sale 8: Untrace.

https://backpack.tf/profiles/76561198135023566#!/compare/1552089600/1552176000

https://backpack.tf/profiles/76561198205845267#!/compare/1557360000/1557360000

Sale 9: Untrace.

https://backpack.tf/profiles/76561198066260405#!/compare/1552953600/1553472000

https://backpack.tf/profiles/76561198091587171#!/compare/1552521600/1556409600

Sale 10: ~20 Keys.

Sold For Miami Nights Frenchman's Beret. (20)

https://backpack.tf/profiles/76561198199457631#!/compare/1556409600/1556582400

https://backpack.tf/profiles/76561197961275685#!/compare/1556409600/1556496000

Sale 11: Untrace.

https://backpack.tf/profiles/76561197961275685#!/compare/1556582400/1556755200

https://backpack.tf/profiles/76561198305494036#!/compare/1556582400/1556668800

Sale 12: Untrace.

https://backpack.tf/profiles/76561198053717045#!/compare/1556582400/1556668800

https://backpack.tf/profiles/76561198016663834#!/compare/1556582400/1556668800

Marketplace.tf Sales:

https://marketplace.tf/items/174;5;u56

Sale 13: ~21 Keys.

Mar 5, 19

$36.99 / $1.79 = 20.66 keys

Sale 14: Low.

Mar 25, 19

$21.40 / $1.78 = 12.02 keys

Usable Sales: 15/16/21/21

Going With 15-21