Sale #1

https://backpack.tf/item/4517376069

Untraceable

https://backpack.tf/profiles/76561199078847021#!/compare/1740268800/1750204800

Sale #2

https://backpack.tf/item/223872979

10 keys

Seller: https://backpack.tf/profiles/76561198913361211#!/compare/1744243200/1744329600 (ID: 15629037165)

Buyer: https://backpack.tf/profiles/76561199199136084#!/compare/1744329600/1744416000

Owned for months, unlikely to be a true quicksell

Sale #3

https://backpack.tf/item/206716414

12 keys + ~1 key in crap

Seller: https://backpack.tf/profiles/76561199085116273#!/compare/1746835200/1746921600 (ID: 15726556483)

Buyer: https://backpack.tf/profiles/76561198874663847#!/compare/1746748800/1746921600

12 + 1 = 13

13

Current sellers:

$26.99 on mp.tf

Sales: 10, 13

It being unsold for 7+ months at $26.99 (only a bit above 13) suggests that the high end is probably a bit high, best to include both sales for a good range.

Final price: 10 - 13