Needs a little drop.

About 7 sellers on backpack.tf for under 13 keys http://backpack.tf/classifieds/?item=Big%20Kill

Sellers for 12 keys, close or lower.

http://www.tf2outpost.com/trade/20658069

http://www.tf2outpost.com/trade/20610139 (12 keys 1 ref)

http://www.tf2outpost.com/trade/20655193 (killstreak big kill with name tag and description for 12 keys)

http://www.tf2outpost.com/trade/20646457 (12 keys 1 ref)

http://www.tf2outpost.com/trade/20643681 (specailized big kill 13 keys, but specialized is worth a key so basically 12 keys)

http://www.tf2outpost.com/trade/20650485

http://www.tf2outpost.com/trade/20639098

http://www.tf2outpost.com/trade/20668913 (12.5)

http://www.tf2outpost.com/trade/20593217

http://www.tf2outpost.com/trade/20666447

http://www.tf2outpost.com/trade/20580890

http://www.tf2outpost.com/trade/20665877 (12.49)

http://www.tf2outpost.com/trade/20611749

http://www.tf2outpost.com/trade/16200136 (95 ref which is 11.2 keys)

Buyers:

http://www.tf2outpost.com/trade/18309451 (for 11 keys)

http://www.tf2outpost.com/trade/17204206 (11 key)

http://www.tf2outpost.com/trade/19570113 (11.5 key)

http://www.tf2outpost.com/trade/19636438 (10.5 key)

http://www.tf2outpost.com/trade/17086173 (7 key.. quickbuyer)

http://www.tf2outpost.com/trade/20385566 (11 key)

http://www.tf2outpost.com/trade/16996134 (11 key)

http://www.tf2outpost.com/trade/19950257 (8 keys.. quickbuyer)

http://www.tf2outpost.com/trade/15082233 (11 keys 2 ref)

http://www.tf2outpost.com/trade/13659715 (10 keys)

http://www.tf2outpost.com/trade/18012822 (8.5 keys.. quickbuyer)

http://www.tf2outpost.com/trade/20295762 (9 keys quickbuyer)

http://www.tf2outpost.com/trade/17202737 (10 keys)

http://www.tf2outpost.com/trade/16292536 (10 keys)

http://www.tf2outpost.com/trade/18488587 (10 keys)

http://www.tf2outpost.com/trade/19213698 (10 keys)

http://www.tf2outpost.com/trade/20199246 (10 keys)

http://www.tf2outpost.com/trade/20342097 (10 keys)

http://www.tf2outpost.com/trade/17455039 (10 keys)

http://www.tf2outpost.com/trade/10072461 (11 keys)

http://www.tf2outpost.com/trade/20377816 (11 keys)

http://www.tf2outpost.com/trade/14100695 (11 keys)

http://www.tf2outpost.com/trade/19006394 (10 keys)

http://www.tf2outpost.com/trade/18506981 (11 keys)

http://www.tf2outpost.com/trade/20401760 (11 keys)

http://www.tf2outpost.com/trade/19056640 (10 keys)

I could go on more, but I won't waste all my time on this suggestion XD.

Hope you can see what im getting here and hope you can see that this needs to go down, that you think i have good proof and this is the right price range! Thanks :)