Sale 1:

Sold for Pro. KS Silver Botkiller Rocket Launcher (Mini at 12 below) + 1 key + ~4 keys in items

http://www.tf2outpost.com/trade/28518560 - B/O of 15

Seller: http://backpack.tf/profiles/76561198021055079#!/compare/1475539200/1475625600

Buyer: http://backpack.tf/profiles/76561198138584731#!/compare/1475280000/1475625600

http://i.imgur.com/6mQFkfD.png

http://i.imgur.com/zmsVnrl.jpg

X = 15 (Capped by B/O)

Sale 2:

Sold for 15 keys

http://www.tf2outpost.com/trade/28503178 - No B/O

Seller: http://backpack.tf/profiles/76561198019556015#!/compare/1475107200/1475193600

Buyer: http://backpack.tf/profiles/76561198216954553#!/compare/1474934400/1475366400

X = 15

Sale 3:

Sold for 14 keys + Strange Chicago Overcoat (1)

No outpost

Seller: http://backpack.tf/profiles/76561198080779894#!/compare/1473638400/1473984000

Buyer: http://backpack.tf/profiles/76561198161887715#!/compare/1473897600/1473984000

X = 15

Pro. KS Silver Botkiller Rocket Launcher:

Sold for 11 keys + ~1 key in painted items in about a day

http://www.tf2outpost.com/trade/28523768 - B/O of 13

Seller: http://backpack.tf/profiles/76561198021055079#!/compare/1475625600/1475712000

Buyer: http://backpack.tf/profiles/76561198057036772#!/compare/1475366400/1475712000

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

http://i.imgur.com/fO1n3MG.jpg

X = 12

No current sellers

Sales at:

15 (3x)

Quickbought mine for 12 keys via my buy order (which, at the time of suggesting, is currently closed due to lack of keys)

Three sales at 15 keys

Going with 15 keys