From your 9 Keys sold:

http://www.tf2outpost.com/trade/17700927 ---> http://www.tf2outpost.com/trade/17869756 Looking for offers, sold to ----> http://www.tf2outpost.com/trade/17875574 B/O 10 Keys, so probably bought it for 9 Keys or less. ----> http://www.tf2outpost.com/trade/17901926 Selling for 10 Keys, probably bought it for ~9 Keys.

9 Keys is a quicksell price. And there isn't proof for 10 Keys sales.

And... http://www.tf2outpost.com/trade/17637656 He don't sold for 12 Keys. ---> http://www.tf2outpost.com/trade/17792923 Looking for Professional Killstreak Rainblower Kit or Fabricator. Offered the C. Warrior for the Fabricator + 4 Keys here: ----> http://www.tf2outpost.com/trade/17683854 Wanted 7 Keys for it. Now he's selling the Collector's for 9 Keys: http://www.tf2outpost.com/trade/17905881

So probably the first guy sold it for ~11 Keys, and the second guy sold it for the Fabricator + ~2 Keys.

Very unstable suggestion. Downvote.