Sale #1

Sold at auction for 11 keys.

Sale #2

Sold on Marketplace.tf for 29.99 USD = 16.2 keys.

Sale #3

Sold on Marketplace.tf for 25.00 USD = 12.9 keys.

Sale #3

bp compare of seller

Sold for 14 keys.

Comparison isn't the most explicit, but I think it's safe to assume it was sold for 14 keys and he bought 2 keys with metal.

Sale #4

bp compare of seller

bp compare of buyer

untraceable

Sale #5

bp compare of seller

bp compare of buyer

untraceable, probably a SCM sale

Sale #6

wizard shit

untraceable

Calling sale #2 for 16.2 keys an outlier because of seller at 16 keys. Taking low value from sale #1 and high value from sale #3.

Going with 11-14 keys.