http://www.tf2outpost.com/trade/9644413 has many offers of around 12-13 keys, and a 14 key offer.

http://www.tf2outpost.com/trade/9018145 has offers of 13 keys and a 15 key offer (trade is 1 month old)

http://www.tf2outpost.com/trade/9497989 has many offers of 12-13 keys for bubbles pug

http://www.tf2outpost.com/trade/10004448 offer of 12 keys, and offer of about 13,5 keys

http://www.tf2outpost.com/trade/9985010 sold for about 13

http://www.tf2outpost.com/trade/9581897 sold for 11.. people complaining how they would do 12 and 13 for it.

Any unusual can sell for 12 keys. :P. i dont know why this hat is under nuts and alot of bad looking effects. I put 12-13 because the 14 and 15 key offers were a month ago and the resent ones were in items. I am still new to this so suggestions will help.