Sale 1:

Sold for Aces High Ketche (Mini at 12 below) + <0.5 keys in items

http://www.tf2outpost.com/trade/28521182 - B/O of 12

Seller: http://backpack.tf/profiles/76561198182585169#!/compare/1475625600/1476057600

Buyer: http://backpack.tf/profiles/76561198285463892#!/compare/1475798400/1475884800

X = 12

Sale 2:

Quicksold for 9 keys + 1 key in items

http://www.tf2outpost.com/trade/28520714 - B/O of 12

Seller: http://backpack.tf/profiles/76561198000091310#!/compare/1475366400/1475452800

Buyer: http://backpack.tf/profiles/76561198182585169#!/compare/1475366400/1475452800

X = 10

Sale 3:

Quicksold for 9 keys + <0.5 keys in items

No outpost

Seller: http://backpack.tf/profiles/76561198285463892#!/compare/1475798400/1475884800

Buyer: http://backpack.tf/profiles/76561198164036774#!/compare/1475798400/1475884800

X = 9

Aces High Ketche Mini:

http://backpack.tf/suggestion/5845a00b83de6b5d975d7931

Sellers:

11 keys:

http://i.imgur.com/iEFtL9n.png

http://www.tf2outpost.com/trade/28563170 - 1 month

http://backpack.tf/profiles/76561198018528305

Sales at:

9

10

12

9 and 10 appear to be quicksell prices. Excluding them from the range.

Seller at 11 keys for a while

Going with 11-12