In favor of this range vs the other suggestion (12.5-13.5) because it is still possible to get it for 12. I have 7 links of sellers at 12 and a couple more at 12.5.

Price was set a month ago. The oldest trades I will use are one week old.

Sellers at 12 keys:

http://www.tf2outpost.com/trade/9538316

http://www.tf2outpost.com/trade/9673851 - courtesy, ArchiteK

http://www.tf2outpost.com/trade/9707898

http://www.tf2outpost.com/trade/9714558

http://www.tf2outpost.com/trade/9508624

http://www.tf2outpost.com/trade/9480033

http://www.tf2outpost.com/trade/9545072 - asked for 13, sold for 12

http://www.tf2outpost.com/trade/9498853 - 12.5 keys

http://www.tf2outpost.com/trade/9715251 - 12.5 keys

http://tf2tp.com/trade.php?trade=9301390 - 13 keys but with three great parts on it

http://www.tf2outpost.com/trade/9518453 - asks for 14, willing to do 13. has robots part on it

Successful Buyers at 12 keys:

http://www.tf2outpost.com/trade/9471132

http://www.tf2outpost.com/trade/9505507

Sellers at 13 keys:

http://www.tf2outpost.com/trade/9696355 - unsold

http://www.tf2outpost.com/trade/9638631 - unsold, no problem getting 12 key pure, 13 key item offer but has trouble selling for 13 pure (still in his bp)

http://www.tf2outpost.com/trade/9576442 - offer of 13 key item (crate 50 was worth this much, conservatively, at the time of offer)

http://i.imgur.com/0LQUCcU.png - sold mine for 13 keys today

http://www.tf2outpost.com/trade/8439345 - 13 key item offer

http://www.tf2outpost.com/trade/9441481 - offer of 13 keys

http://www.tf2outpost.com/trade/9637984 - sold for 13

http://www.tf2outpost.com/trade/9463250 - multiple 13 key offers

http://www.tf2outpost.com/trade/9696615 - 13.5 key item offer

http://www.tf2outpost.com/trade/9694361 - added for 14 keys 1 day ago? still in his bp, though...

http://www.tf2outpost.com/trade/9616402 - 16 keys... clearly an outlier

Will post more as I look em up. 13 keys is doable, but is not a gimme as indicated in the other suggestion. 12 keys go fast, but it is still possible to get for that.