Sale 1:

Sold with a key and an insulated inventor for Bubbling Valley Forge (16.5)

No trade on the Sultan’s, but had a B/O of 14 on the Valley:

http://www.tf2outpost.com/trade/28229208

Seller: http://backpack.tf/profiles/76561198066071644#!/compare/1464825600/1464912000

Buyer: http://backpack.tf/profiles/76561198175870879#!/compare/1464825600/1464912000

X = 14 (Capped by B/O)

Sale 2:

Sold for Terror-Watt Bonk Helm

http://www.tf2outpost.com/trade/28254342 - No B/O

Seller: http://backpack.tf/profiles/76561198073753471#!/compare/1466467200/1466553600

Buyer: http://backpack.tf/profiles/76561198116664193#!/compare/1466467200/1466553600

X = 14

Sale 3:

Sold for Stormy Carouser’s Capotain

No outpost

Seller: http://backpack.tf/profiles/76561198168316519#!/compare/1464566400/1464652800

Buyer: http://backpack.tf/profiles/76561198066071644#!/compare/1464566400/1464652800

X = 11

Sellers:

14 keys:

http://www.tf2outpost.com/trade/28276432 - young

Sales at:

11

14

14

11 looks like a bit of an outlier

Going with 14 flat