Oy I'm blind.

https://backpack.tf/item/3343592041

Sale 1) Bulk sale for something

https://backpack.tf/profiles/76561198039217749#!/compare/1528070400/1528243200

https://backpack.tf/profiles/76561197994697258#!/compare/1527984000/1528070400

https://backpack.tf/item/2540667743

Sale 2) I would presume this was 7 Keys, as the Buyer has a Buy Order at 7 Keys

https://backpack.tf/profiles/76561198126946758#!/compare/1529107200/1529193600

https://backpack.tf/profiles/76561198121830870#!/compare/1529107200/1529193600

Low outlier.

https://backpack.tf/item/5862735526

Sale 3) Sold for 8 Keys + 2 Refined

https://backpack.tf/profiles/76561198001302864#!/compare/1523923200/1524009600

Rounds to 8 Keys

Low outlier.

Sale 4) Sold for 8 Keys + 15 Refined

https://backpack.tf/profiles/76561198309332284#!/compare/1527638400/1527724800

https://backpack.tf/profiles/76561198074745301#!/compare/1527724800/1527811200

Rounds to 8.5 Keys

https://imgur.com/a/JCTEN7J - 16 Day Seller at 9 Keys, 26 Day Seller at 9.74 Keys, and a 29 Day Seller at 10 Keys (the picture is a day old, listings still here)

https://backpack.tf/item/2540667743

https://backpack.tf/item/6267513680

https://backpack.tf/item/3343592041