Josef Stalin

https://backpack.tf/item/4932489349

Sale 1) Sold for a Flaming Lantern Brown Bomber (60 Keys) + Smoking Exquisite Rack (37.5 Keys)

https://backpack.tf/profiles/76561198114402400#!/compare/1523750400/1523836800

60 + 37.5 = 97.5, which rounds to 98 Keys

Sale 2) Sold for 37 Keys + Searing Plasma Private Eye (25 Keys) + Vivid Plasma Conquistador (21 Keys)

https://backpack.tf/profiles/76561198126724119#!/compare/1524268800/1524355200

37 + 25 + 21 = 83, which I'll round to 85 Keys

Private Mini

https://backpack.tf/suggestion/5b300cc8cf6c7573f25259c4 - 25 Keys

Conquistador Mini

https://backpack.tf/suggestion/5b31629544325a584a1c10da - 21 Keys

https://backpack.tf/item/4823853606

Sale 3) Sold for $199.99 when Keys were ~$1.98 each

https://marketplace.tf/items/30743;5;u16

199.99 / 1.98 = 101.005, which I'll round to 100 Keys