Okay, let's go to set a price for this unusual. I have been one of the owners but I know for how much has been sold each time.

Three have been unboxed, but at the moment there is only one at the market, he has a ridiculous B/O anyway: http://www.tf2outpost.com/trade/11623728

1) I bought it from NO TF2 :C °_̯͡° ÅlPiNɛ ΩwNɛR★ツ☆ for a Purple Energy Salty Dog (2.1 - 2.7 buds right now, but the price was 2.5 - 3.2 buds then) and he added a Strange Original and a Strange Festive Frontier Justice as sweets on 20 may. Taking unusual overpay and the sweets, it was around 2.8 buds, the lowest purchase. Proof: http://i.imgur.com/dVe2Zs4.png?1 He got it 2 days ago from a friend for some weapons and crap: http://i.imgur.com/SLdhe2y.png

2) I sold the hat the same day to [LCD] Rimpula for a Max's (with Die Job Spectrum, Maxs were 2.2 - 2.4 buds), 27 keys, 10 robokeys, a clean All-Father, a clean Kringle, a clean Fast Learner (with Die Job too) and 12 robocrates. Buds were 23.5 keys and it was easy to sell a robokey for 1.5 keys (I sold the 10 robokeys for 15 regular keys the same day), so I got around 4.5 buds, the highest purchase. Proof: http://i.imgur.com/RjBFxXT.png?1 and http://i.imgur.com/dyj00A1.png?1

3) [LCD] Rimpula sold it 2 days ago to wa7er, the current owner, for a Holiday Headcase (2.8 - 3 buds).

Conclusion: the lowest purchase was around 2.8 - 3 buds and the highest purchase at 4.5 buds. I know the range is a bit weird but this is the history from the last owners.

All the comments are welcome!