This needs an update.

Using my two sales :P

Sale #1:

I bought it for a Green Confetti Carouser's Capotain (1.1 buds):

http://www.tf2outpost.com/trade/25069111

http://m.imgur.com/hr01L4r

Carouser:

http://m.imgur.com/29TojLH

Head Warmer:

http://m.imgur.com/tYI8pwZ

Total: 1.1*0.9 = ~1 bud

Sale #2:

I then traded it for a Nuts n' Bolts Towering Pillar of Hats (17 keys, see mini):

http://www.tf2outpost.com/trade/25310847

http://m.imgur.com/dQQ5I95

Towering Pillar of Hats:

http://m.imgur.com/vc1aNST

Head Warmer:

http://m.imgur.com/1YJSErt

Total: 17 keys (~1.5 buds)

No overpay because I offered it on the Tower as you can see in the trade

Mini Suggestion for the Nuts n' Bolts Towering Pillar of Hats because it is outdated:

http://www.tf2outpost.com/trade/25342403

http://m.imgur.com/AuAQei8

Tower:

http://m.imgur.com/femK5YN

Total: 1 bud (11 keys) + 6 keys + 8.55 refined (~0.5 keys) = 17.5 keys

B/O was 17 keys