Plumber's Crack

https://backpack.tf/item/4880522143

Sale 1) Sold for 8 Keys?

https://backpack.tf/profiles/76561198089292580#!/compare/1523232000/1523318400

zol has a Buy Order at 8.36, so I'd imagine the sale is that.

Sale 2) Sold for 8 Keys + 17 Refined

https://backpack.tf/profiles/76561198306916766#!/compare/1527897600/1528416000

Rounds to 8.5 Keys

https://backpack.tf/item/2942721436

Sale 3) Sold for ?

https://backpack.tf/profiles/76561198366487245#!/compare/1526860800/1526947200

Again, probably to the Buy Order at 8.36 Keys

https://backpack.tf/item/644621405

Sales 4 and 5) Sold for 8 Keys + 10 Refined and 8 Keys + 18 Refined

https://imgur.com/a/NKQ7at8

https://backpack.tf/item/1362623575

Sale 6) Sold for 8 Keys + 19 Refined

https://imgur.com/a/NKQ7at8

Rounds to 8.5 Keys

Sale 7) Sold for 8 Keys

https://backpack.tf/profiles/76561198047988796#!/compare/1526688000/1526774400

Low outlier

Sale 8) Sold for ?

https://backpack.tf/profiles/76561198047988796#!/compare/1527465600/1527724800

Again, probably to the Buy Order at 8.36 Keys.

Rounding 8.36 to 8.5 Keys.