Took some proof from this suggestion: http://backpack.tf/vote/id/527aade54cd7b823528b456b

Sellers below 14 keys:

13 keys: http://www.tf2outpost.com/trade/15777800 ; http://www.tf2outpost.com/trade/15539169

13.3: http://www.tf2outpost.com/trade/15429733

13.5 keys: http://www.tf2outpost.com/trade/15770506

For 14 keys, has an expensive part (headshot kills): http://www.tf2outpost.com/trade/15774601

Solds:

Quicksold for 12: http://puu.sh/5l1OL.png ; http://www.tf2outpost.com/trade/15763428; http://www.tf2outpost.com/trade/15753672 --> sold to http://www.tf2outpost.com/trade/11731599

Bought one for 12, rejected offer of 13 keys: http://www.tf2outpost.com/trade/15730069 ; bought this one: http://www.tf2outpost.com/trade/15765791

12.5: http://puu.sh/5l2xZ.png

12.8: http://bazaar.tf/trade/540104 ; (12.5): http://puu.sh/5l29q.png

13 keys, reseller, had parts: http://www.tf2outpost.com/trade/15769854

13: http://www.tf2outpost.com/trade/15752753; sold 2: http://www.tf2outpost.com/trade/15507359

Possibly 14: http://www.tf2outpost.com/trade/15745221

14: http://www.tf2outpost.com/trade/15467094 ; http://oi43.tinypic.com/155mivd.jpg - 10 days ago (credit geos to: http://backpack.tf/u/76561198020235082 )

15.5 keys: http://www.tf2outpost.com/trade/15327907 , http://i.imgur.com/7Yc0rJC.png - 2 weeks ago (credit goes to: http://backpack.tf/u/76561197961421166 )

Notable offers:

11 keys + S. Original (~2.8 keys) ~ 13.8 keys, not sold: http://www.tf2outpost.com/trade/15752213

Unsolds

(Hard to find some, many lower their price regulary)

14 keys, probably not sold for 8 days: http://www.tf2outpost.com/trade/15453034

--> Many for below 13.5 keys, but below or around 13 seems very quick; also a few have success for 14, seems more to tend around 13 or even 12-13, but they sell very quick for this atm, so I feel like 14 should still be included.

Let me know what you think, thanks.