Credits to Scourge.

Sales

Sale 1: Sold for 15 keys + 3 ref

https://backpack.tf/profiles/76561198318587422#!/compare/1596585600/1596672000

https://backpack.tf/profiles/76561198267189538#!/compare/1596585600/1596672000

15 keys~

Sale 2: Sold for 16 keys

https://backpack.tf/profiles/76561198267189538#!/compare/1596931200/1597017600

https://backpack.tf/profiles/76561198059874094#!/compare/1596844800/1597017600

Sale 3: Bulk

https://backpack.tf/profiles/76561198059874094#!/compare/1597017600/1597104000

https://backpack.tf/profiles/76561198255764866#!/compare/1596931200/1597017600

Sale 4: Sold for Gfetti Tipped Lid (17 keys) + 2 keys

https://backpack.tf/profiles/76561198255764866#!/compare/1597276800/1597363200

https://backpack.tf/profiles/76561198170139169#!/compare/1597276800/1597363200

17 + 2 = 19 keys

Tipped Lid:

https://backpack.tf/suggestion/5f431b10a4add932163566fe

Sale 5: Sold for 18 keys

https://backpack.tf/profiles/76561198170139169#!/compare/1597449600/1597536000

https://backpack.tf/profiles/76561198159382373#!/compare/1597449600/1597536000

Sale 6: Sold for 18 keys

https://backpack.tf/profiles/76561198159382373#!/compare/1597449600/1597536000

https://backpack.tf/profiles/76561198076218381#!/compare/1597449600/1597536000

Marketplace

https://marketplace.tf/items/tf2/434;5;u8

Nothing recent.

Classifieds

https://gyazo.com/4f626bad12eee37b25a25d0e96e75d7d

Buyers are around 17.9~.

Summary

Sales are at 15, 16, 18, 18, and 19.

Conclusion

Going to exclude sales at 15 and 16 due to buyers.

17.9 is very close to buyers, but there's 2 sales at 18 here, going to include 18 here.

Going to go with 18-19 here.