Resuggesting a Third time, ( first suggestion give me a break :D)

Not many of these are on the market.

I Bought one for 6 ref (I added the paint later, it wasn't painted when I bought it)

http://imgur.com/LuaDMFX

This guy is selling one but not really replying to anyone

http://www.tf2outpost.com/trade/21450971

He got contacted about this hat right off the bat.

(Apparently Spu bought this)

Spu Sold one for a key

http://www.tf2outpost.com/trade/21748609#latest

One bought for 3.88

http://i.imgur.com/uEZk25b.png

I believe buying for a 3.88 was very lucky, so lets consider it an outlier and give a 0.8 - 1 key

There are very little craftable unique on the market, so a little bump of price may be in order.(0 on outpost, 0 on Bazaar)