Sold for 50 Pure + a Disco Beat Down Bear Necessities (20.5 keys)

50 + 20.5 = 70.5 rounding to 70

https://backpack.tf/suggestion/5d80efb2d3817204fc522e2b <- Mini for the Bear Necessities

The Buyer gave the Bear Necessities (20.5 keys) as a down payment for him to hold onto the hat and then gave him 50 keys pure later on.

https://backpack.tf/profiles/76561198303975530#!/compare/1563494400/1566259200 <- Disco Beat Down Bear Necessities (Check History)

https://backpack.tf/profiles/76561198303975530#!/compare/1567555200/1567728000 <- Keys

https://backpack.tf/profiles/76561198026129220#!/compare/1567641600/1567728000 <- Keys (Check History)

Other sales are all unusable.

Bulk key sale

https://backpack.tf/profiles/76561198260430989#!/compare/1560902400/1563753600

https://backpack.tf/profiles/76561198308772967#!/compare/1563667200/1563753600

(Even if usable, the seller appears to be an alt of a scammer).

Unknown/untrace

https://backpack.tf/profiles/76561198308772967#!/compare/1564099200/1564444800

https://backpack.tf/profiles/76561198026129220#!/compare/1564012800/1564185600

Sold to a scammer/got scammed

https://backpack.tf/profiles/76561198084976847#!/compare/1562284800/1563753600

https://backpack.tf/profiles/76561198869851998#!/compare/1563580800/1563753600

Thanks to surs for helping me.