Resuggesting, thanks for the info, K1ng!

Sale 1:

https://backpack.tf/profiles/76561198337734785#!/compare/1572998400/1573084800

26 keys

Sale 2:

https://backpack.tf/profiles/76561198057897812#!/compare/1574553600/1574726400

https://backpack.tf/profiles/76561198363395191#!/compare/1574467200/1574553600

idk

Sale 3:

https://backpack.tf/profiles/76561198088775634#!/compare/1574467200/1574726400

idk

Marketplace sales:

https://marketplace.tf/items/tf2/30121;5;u58

https://marketplace.tf/items/tf2/5021;6

59.99$ on Nov 27th

59.99/1.73=34.67= 35 keys

https://backpack.tf/item/7957046349

Only history I could find for marketplace sale

Quoting K1ng: "Marketplace sales were $40 (~23 keys) and $59.99 (~35 keys). The latter could be an outlier, but the first could have quicksold.

A conservative drop to 23-35 should work I guess."

23-35 keys