Resuggesting, new sales here. (Thanks to myself :P)

Sold for 24 keys

https://backpack.tf/profiles/76561198254025117#!/compare/1587340800/1587686400

https://backpack.tf/profiles/76561198262254987#!/compare/1587600000/1587686400

Sold with Purple Confetti Crit Cloak for Circling TF Logo Law

https://backpack.tf/profiles/76561198045655893#!/compare/1586390400/1587254400

https://backpack.tf/profiles/76561198254025117#!/compare/1587081600/1587254400

Bulk

Bulk for Purple Energy Cotton Head

https://backpack.tf/profiles/76561198045655893#!/compare/1585440000/1585785600

https://backpack.tf/profiles/76561198176405094#!/compare/1585699200/1585785600

Sold for Bubbling Cloud Crasher (11 keys) + Vintage Lugermorph (6 keys) + Specialized Killstreak Festive Ambassador (0.97 keys)

https://backpack.tf/profiles/76561198176405094#!/compare/1585008000/1585180800

https://backpack.tf/profiles/76561198069493147#!/compare/1585094400/1585180800

11 + 6 + 0.97 = 17.97 rounding to 18 keys

Open Suggestion for the Cloud Crasher:

https://backpack.tf/suggestion/5eb9a6bbf7eccf4a2f4b47c7

Sold for 8 keys, likely more but doesn't show.

https://backpack.tf/profiles/76561198069493147#!/compare/1585008000/1585094400

https://backpack.tf/profiles/76561198305494036#!/compare/1585008000/1585094400

Unknown

https://backpack.tf/profiles/76561198046334647#!/compare/1584144000/1585180800

https://backpack.tf/profiles/76561198305494036#!/compare/1584057600/1584144000

Sold for 36 on March 24, 2020 (36/1.68 = 21.42 rounding to 21 keys)

https://marketplace.tf/items/tf2/30162;5;u16

Untrace

https://backpack.tf/profiles/76561198037484203#!/compare/1590624000/1590710400

https://backpack.tf/profiles/76561198021228339#!/compare/1589587200/1590624000

Sold for 19 keys

https://backpack.tf/profiles/76561198021228339#!/compare/1590796800/1590883200

https://backpack.tf/profiles/76561198100893394#!/compare/1590796800/1591228800

ID's match.

Not sure, the sellers bp comparison is not updated?

https://backpack.tf/profiles/76561198100893394#!/compare/1590796800/1591228800

https://backpack.tf/profiles/76561198019257028#!/compare/1591142400/1591315200

Classifieds:

https://gyazo.com/1af4705149a414f676b5cd5ee383ce6b

1 @ 18 keys

1 @ 19 keys

1 @ 21 keys

1 @ 24 keys

Seller at 22 keys, for 2 months. Excluding 24.

Taking a range of 18-21 keys here.