Rich

https://backpack.tf/item/2253240042

Sale 1) ?

https://backpack.tf/profiles/76561198090956917#!/compare/1563667200/1563753600

https://backpack.tf/item/3935487971

Sale 2) Sold for random items

https://backpack.tf/profiles/76561198104429219#!/compare/1564272000/1564444800

Sale 3) Sold + ~0.4 Keys of Items for a Tesla Coil Wing Mann (9.75 Keys)

https://backpack.tf/profiles/76561198204884524#!/compare/1564358400/1564444800

https://backpack.tf/profiles/76561198971152948#!/compare/1564358400/1564444800

9.75 - 0.4 = 9.35, which rounds to 9.5 Keys

Sale 4) ?

https://backpack.tf/profiles/76561198971152948#!/compare/1564444800/1564531200

https://backpack.tf/profiles/76561198346897149#!/compare/1564444800/1564531200

Sale 5) Bulk sale for a Purple Energy Federal Casemaker

https://backpack.tf/profiles/76561198346897149#!/compare/1564704000/1564790400

https://backpack.tf/item/2554533418

Sale 6) Bulk sale for a Bonzo-the-All-Gnawing Sober Stuntman

https://backpack.tf/profiles/76561198102298516#!/compare/1561075200/1561248000

Sale 7) Sold for $19.99 when Keys were ~$1.82 each

https://marketplace.tf/items/tf2/403;5;u60

https://marketplace.tf/items/tf2/5021;6

19.99 / 1.82 = 10.98, which rounds to 11 Keys

https://backpack.tf/item/2383961939

Sale 8) Sold for 8 Keys to a buy order

https://backpack.tf/profiles/76561198163326982#!/compare/1538265600/1562112000

Sale 9) ?

https://backpack.tf/profiles/76561198323565601#!/compare/1563494400/1563580800

https://backpack.tf/profiles/76561198066970734#!/compare/1563494400/1563580800

https://backpack.tf/item/2215768098 - Can't figure any of the sales out here

https://imgur.com/a/HXPRMDt - 8 Day Seller at 10 Keys

https://imgur.com/a/ZHZvjXp - 2 Sellers ~10 Keys. Pyro's has been up for 1 day and sujak's has been up for 2 weeks

https://backpack.tf/item/2463001487

https://backpack.tf/item/2253240042

https://backpack.tf/item/3935487971

Given the number of Sellers at 10 Keys, I'm calling the 11 Key Marketplace sale high and going with 9.5 Keys flat.

Calling 8 low as it went to a buy order.