The price for this Unusual is 4 months old and in need of a bump. I'll try to keep things quick.

Not a whole lot of demand for one of these unusuals. There's only one current single listing on TF2OP: http://www.tf2outpost.com/trade/9129604

The seller is taking offers for it, though it appears as if he wants at least 13 keys, judging by the fact that he's turned down offers of 12 keys and liked a potential offer of about 14.5 keys, though he turned it down because he said he didn't want to sell the items. So the range looks fine for now, judging by what little we have.

Also, while this was 2 months ago, it might be useful to have around: http://www.tf2outpost.com/trade/7307220

The seller wanted 2 pure Bill's Hats (preferrably unpainted) for the hat (painted pink), which would equate to 16 keys (15 w/o the paint). The listing was closed, and it apparently sold, but I can't find confirmation of the sale (or who it went to). To further complicate things, examination of their inventory reveals nothing close to items adding up to 16 keys. There is a White Bill's, but that's the only one they have.

So it seems as if the range of 13-14 keys can stay for now. The seller is looking in that range, and the second one that allegedly sold, if it was, probably sold for less than the buyer was asking for.