3 months old, needs an update. Resuggesting with better range.

http://www.tf2outpost.com/trade/19998023 - Quicksold for 9 keys (OUTLIER)

http://www.tf2outpost.com/trade/20029234 - Quicksold for 10 keys+ in items (~9 keys with overpay, OUTLIER)

http://www.tf2outpost.com/trade/20016292 - Offered 11 keys

http://www.tf2outpost.com/trade/19898329 ---> http://www.tf2outpost.com/trade/19910834

Sold for Nuts Stove Pipe (14 keys * 0.9 = 12.6, rounding to 13)

http://www.tf2outpost.com/trade/19833958 - Sold for 12+ keys in items (12 * 0.9 = ~11)

http://www.tf2outpost.com/trade/19381693 - Unknown what sold for

Thats a lot of solds there XD

To sum up: Quicksales at 9, sales at 11 and 13 and a pure offer of 13. 9 key sales were quicksales, so let's go with the range 11-13 keys.