It's 1 of 1 in existence. http://steamcommunity.com/id/syxx66/inventory/#440_2_1671416698 Bought it directly from the unboxer, kaos, for 50 earbuds pure.

Xaero was kind enough to supply me screenshots of his trade history: http://imgur.com/qcm422G http://imgur.com/9gQyCUK

This hat has literally only been traded once, but this is the price it went for. (For what it's worth, it's currently not for sale and Xaero told me he would decline 50 buds if someone offered that to him today, because he's a collector.)