Little bit here.

Sales

Sale 1: Untrace

https://backpack.tf/profiles/76561198363395191#!/compare/1597017600/1597104000

https://backpack.tf/profiles/76561198163695967#!/compare/1596758400/1597881600

Other exchanges, such as scrap, marketplace, and etc.

https://backpack.tf/item/7957656844

https://backpack.tf/item/7956985445

Marketplace

https://marketplace.tf/items/tf2/30394;5;u58

July

$42.09 on July 2 (42.09/2.01 = 21~)

https://manic.tf/keyprice/?at=2020-07-02

Listings during the time: https://bot.tf/stats/listings/4EP2R81K

40 on July 3 (40/2 = 20)

https://manic.tf/keyprice/?at=2020-07-03

Listings during the time: https://bot.tf/stats/listings/MLV732ZZ

23.02 on July 6 (23.02/1.99 = 12~)

https://manic.tf/keyprice/?at=2020-07-06

Listings during the time: https://bot.tf/stats/listings/4EP5006E

34.95 on July 27 (34.95/1.92 = 18~)

42.09 on July 27 (42.09/1.92 = 22~)

Buyout was probably 21.

https://manic.tf/keyprice/?at=2020-07-27

Listings during the time: https://bot.tf/stats/listings/4P0QGGZE

August

$52.78 on August 20 (52.78/1.79 = 29~)

https://manic.tf/keyprice/?at=2020-08-20

Classifieds

https://gyazo.com/6476c204a998f4080aa6483c2ca7b589

Buyers up to 15 keys~.

Summary

Marketplace sales at 12, 18, 20, 21, 21, and 29.

Conclusion

12 is under buyers, excluding.

29 seems like a high outlier considering the past sellers around 20/21/22.

Going with 18-21 here.