Sale 1: (credits to paradoX for providing the sale)

Sold for 30 buds (buds were 10 keys) = 300 keys

http://www.tf2outpost.com/trade/25383407

Sale 2: (credits to paradoX for providing the sale)

Sold for 31 buds (buds were 10 keys) = 310 keys

http://www.tf2outpost.com/trade/25424028

http://backpack.tf/profiles/76561198037924580?time=1426921200

Sale 3: (credits to aaroncsn for providing the sale)

Sold for 342 keys

http://www.tf2outpost.com/trade/24874459

http://backpack.tf/profiles/76561198042536351?time=1423959450 → http://backpack.tf/profiles/76561198042536351?time=1423987200

Notes:

Previous suggestion: http://backpack.tf/vote/id/550e8031ba8d88f5188b4b6c

Only pricing this hat with clean sales.

Conclusion:

Sales at 300, 310 and 342 keys. Taking a range of 300-342 keys. (pure sales shouldn't be rounded)

Feel free to support/counter my suggestion!