In the dark.

Sale 1: Sold for 20 keys

https://backpack.tf/profiles/76561198212303883#!/compare/1568592000/1568764800

https://backpack.tf/profiles/76561198195597491#!/compare/1568592000/1568764800

Counted 20 that match.

Buyout was 27 keys

https://bot.tf/stats/listings/MQ9Q2G1Q

Sale 2: Sold for 23 keys

https://backpack.tf/profiles/76561198194519291#!/compare/1571097600/1571270400

https://backpack.tf/profiles/76561198327145959#!/compare/1571270400/1571356800

Sale 3: Sold for dbd boonie

https://backpack.tf/profiles/76561197967833955#!/compare/1570233600/1570320000

https://backpack.tf/profiles/76561198194519291#!/compare/1570233600/1570320000

Boonie is outdated. Mini at 24.5 keys. Rounding to 25 keys

Mini for dbd boonie

https://backpack.tf/suggestion/5db2704cd381720c7634fa18

Sale 4: Not sure

https://backpack.tf/profiles/76561198090520837#!/compare/1568851200/1568937600

https://backpack.tf/profiles/76561198987144033#!/compare/1568851200/1568937600

Sale 5: Sold for 36.99 on august 23

https://marketplace.tf/items/tf2/318;5;u10

https://backpack.tf/item/287813647

36.99/1.82 = 20.32 rounding to 20 keys

Classifieds:

https://gyazo.com/a313ca4bf461b951f330eec8df70e252

Conclusion:

Sales at 20, 23, and 25. Marketplace sale at 20.

Taking 20-25 keys.