Resuggesting, thank you Xergoyf.

Sales

Sale 1: Untrace

https://backpack.tf/profiles/76561198412841776#!/compare/1597276800/1597363200

https://backpack.tf/profiles/76561198105071091#!/compare/1597276800/1597449600

Sale 2: Sold for 7 keys + 4 refined

https://backpack.tf/profiles/76561198980897882#!/compare/1597276800/1598313600

https://backpack.tf/profiles/76561198412841776#!/compare/1597190400/1597276800

7 keys~

Sale 3: Sold with 21.78 refined (0.459 keys~) of items~ for Smoking Shooter's Sola Topi (7.75 keys) + ~2.75 keys in adds

https://backpack.tf/profiles/76561198093697268#!/compare/1596931200/1597104000

https://backpack.tf/profiles/76561198980897882#!/compare/1596931200/1597104000

7.75 - 0.459 + 2.75 = 10 keys~

Topi: https://backpack.tf/suggestion/5f49cf28f0fb564f6230d589

Sale 4: Sold for 8 keys

https://backpack.tf/profiles/76561198850274253#!/compare/1596326400/1596412800

https://backpack.tf/profiles/76561198093697268#!/compare/1596326400/1596412800

Marketplace

https://marketplace.tf/items/tf2/30093;5;u18

August

$17 on August 14 (17/1.8 = 9.5 keys~)

https://manic.tf/keyprice/?at=2020-08-14

Classifieds

https://gyazo.com/7749fb38c564b25cff71f9d50a691f7e

Summary

Sales at 7, 8 and 10.

Marketplace sale at 9.5.

Conclusion

The sale for 10 then resold for 7 (sale 2), excluding both.

Going with 8-9.5 here.