Updating a 4 month old price on this hat (that I own). Just 1 up on outpost, there have been a couple recent sales as this hat does not come up on outpost very commonly.

http://www.tf2outpost.com/trade/13409945 - B/O 4.7 buds

Sold for L46 Max(~2.2) + 2 buds + 2 keys = ~4.3 buds

BP after trade: http://backpack.tf/id/76561198003481121?time=1375858800

As well as the fact that he was offered "~4 in promos" from the buyer on his outpost trade.

Looks like he originally bought the hat for O. Fire Bonk Boy(~3) + Bliz Geisha(~15 keys) + 11 keys = ~4.2 buds

Proof: http://backpack.tf/id/76561198003481121?time=1374994800 -> http://backpack.tf/id/76561198003481121?time=1375081200

The bonk is an outdated price, but here http://www.tf2outpost.com/trade/13310766 there are willing buyers for 3 and 3.2 pure very recently.

Current owner on outpost has no notable offers.