Well, let's share some info fot this hat.

It has pretty short history, but anyway.

I had this hat before and sold it for Harvest Moon Coupe + 1 bud + 15 keys (sold on the tf2-trader unusual trade server)

Proof: http://imgur.com/a/ePsxr

3.5 + 1 + 0.8 = 5.3

Bought it for SBTWC Big Country (paid 4 buds for it, was first real owner http://imgur.com/a/RYtFU ) + ~16 keys as sweets

Proof: http://imgur.com/a/NLDqP

This is the trade: http://www.tf2outpost.com/trade/17675643

4 + 0.8 = 4.8

Lately it was sold in the mixed offer for misty skull yellow belt. And this guy asking for just 3.5

http://www.tf2outpost.com/trade/19722539

UPD: just bought it back for the coupe alone, lol :D

More info:

http://www.tf2outpost.com/trade/18456771

was offered GBH Hermes (4 buds)