http://www.tf2outpost.com/trade/20883166 - sold one for a steaming ushanka (~13 keys)

http://imgur.com/eef5OsL

http://www.tf2outpost.com/trade/20865021 - sold for 11 keys (5 days)

http://www.tf2outpost.com/trade/20423628 - sold for an aus. axtinguisher (~12 keys)

http://backpack.tf/profiles/76561198075927318?time=1403852400 / http://backpack.tf/profiles/76561198075927318?time=1404284400

http://www.tf2outpost.com/trade/20925663 - sold for a spk s original (? - roughly 8 keys), had a b/o of 11, was offered a steaming hetman's

http://backpack.tf/profiles/76561198021854431?time=1404370800 / http://backpack.tf/profiles/76561198021854431?time=1405062000

http://www.tf2outpost.com/trade/21074086 - sold for a gifted steaming berliner's, which was then sold for an o fire toe (~13ish keys)

*previous berliner's owner was willing to sell for 10 - http://www.tf2outpost.com/trade/21073744

http://www.tf2outpost.com/trade/21080324 - sold for a planets hot dogger (~14 keys - sweets were added on the knot's side?), was bought for a nuts lil buddy (~11 keys)

http://backpack.tf/profiles/76561198028120728?time=1404716400 / http://backpack.tf/profiles/76561198028120728?time=1404802800

~~~~~

http://www.tf2outpost.com/trade/21133875 - 14 keys (3 days) - offered 10 keys

http://www.tf2outpost.com/trade/21016128 - 14 keys (1 week) - no offers

http://www.tf2outpost.com/trade/21097879 - 14 keys (4 days) - no offers

http://www.tf2outpost.com/trade/21177664 - 13 keys (1 day)

http://www.tf2outpost.com/trade/21133278 - quicksold for 9 keys

~~~~~

http://backpack.tf/vote/id/53b888244cd7b811398b4787 - according to germanwalrus's comment, he has bought 2 at 10 keys each as well

Most sales are around the 11-13 keys range with the midpoint and lower-end being a bit more frequent