I like pricing Pencil Pushers. Especially rare ones.

1 of 2, other owner is never selling (he's had in his profile description for almost a year that he isn't selling). The guy who just bought it isn't selling either, so one sale should suffice.

http://www.tf2outpost.com/trade/25640155 -sold for 125 keys, easy :D (I would confirm the exact amount with the backpack history, but he seems to have immediately bought some of the stuff with some of the keys he got from the sale, and the buyer's backpack history isn't complete enough, but he does appear to have had a lot of keys a few days before the trade: https://backpack.tf/profiles/76561198066574786?time=1429599600 and none after: https://backpack.tf/profiles/76561198011240424?time=1429599600 )

As usual, if there is anything wrong with this suggestion please tell me and I will try to fix it! Thanks in advance and have a nice day :)