Don't mind me, just raising the price of my own unusual. But seriously, I've been keeping track of sales, and there does need to be a small rise.

http://www.tf2outpost.com/trade/11633054 Offer of a Bubbling Grimm Hatte (~23.5 keys) + sweets. This trade went through.

http://www.tf2outpost.com/trade/11609306 Same offer of Grimm Hatte. There's also an offer of an N&B Ol' Geezer + Strange Huntsman, which ends up around 22 keys. Also a turned down Planets Crocleather, about 17.5 keys.

http://www.tf2outpost.com/trade/11257924 Sold for 17 Keys + Festive Medigun, ~19 keys.

http://www.tf2outpost.com/trade/13187139 Offer of Smoking Birdcage, ~20 keys, + sweets.

http://www.tf2outpost.com/trade/12524431 Sold for 15 pure + 3.5 keys of sweets, ~18.5.

http://www.tf2outpost.com/trade/12855438 B/O of 18 keys, but since there's an offer of 18 keys noted as the c/o, I'm inclined to believe the OP may have confused c/o and b/o. Regardless, it's an offer of 18 keys.

It's clear that 17 keys is not an occurring price, and that sales occur mostly around 18.5-20 keys. However, the 22 key offer and 23.5 key sale prove that higher is possible, and the possibly 18 key B/O show that there may be a seller at slightly lower. I've put the high end at 22 keys, just in case the 23.5 sale was an exceptional occurrence.

inb4 shitstorm