This is the first suggestion with proof on this hat! Anyway, I had a poke around and found all the proof I could find for this hat up to 1 year (last suggestion).

There are 6 in existence with 2 on the market currently.

http://www.tf2outpost.com/trade/13268946

- 1.4 bud offer

http://www.tf2outpost.com/trade/12051037

- Sold for 1 bud (23 keys at the time)

http://www.tf2outpost.com/trade/10326985

- sold for 25 keys worth of items

http://www.tf2outpost.com/trade/9697079

- Sold for 1 bud

http://www.tf2outpost.com/trade/8026279

- Sold for 2 SF weapons (24 keys worth) + 15 keys = 39 keys = 1.7 buds (outlier)

Current trades

http://www.tf2outpost.com/trade/13431934

- Selling as a set

http://www.tf2outpost.com/trade/13393709

- Young trade with no offers

Let me know what you think!

Thanks!