Several people said that the range should be 13-14 instead of 12-14 on my last suggestion, so here is my proof from last time:

2 on outpost, and only one with offers:

http://www.tf2outpost.com/trade/9988441

Although the b/o is ridiculous, there are several offers of 12 keys and above (pure) and unusuals over this price range

-15 keys pure

-13 keys pure

- retracted 16 keys

-bubbling Magistrate's Mullet (14-16 keys)

-big kill if seller adds a key

- 7 keys, ebenezer, dashin hashashin painted (not sure what paint), gold mk.II knife, and possible other hats/miscs

Also, buyers don't seem to be accepting 12 keys:

http://www.tf2outpost.com/trade/10739728

http://www.tf2outpost.com/trade/10661057