1 sale

1) The Ooze Brain-Warming Wear (38) + Circling Peace Sign Backbiter's Billycock (16)

https://backpack.tf/profiles/76561198826855147#!/compare/1552694400/1552780800

https://backpack.tf/profiles/76561198285293881#!/compare/1552694400/1552780800

Brain sold for Orbiting Planets Blighted Beak (38)

https://backpack.tf/profiles/76561197971485686#!/compare/1552953600/1553040000

https://backpack.tf/profiles/76561198064982470#!/compare/1552953600/1553040000

Beak sold for $70 on February 9th, keys were $1.82

https://marketplace.tf/items/315;5;u32

70/1.82 ≈ 38 keys

Billycock

https://backpack.tf/suggestion/5c536970cf6c754d1b286acf

38 + 16 = 54

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Total: 54

If you will find other sales, you're welcome to report them.