Sale 1:

Sold for $27 on Marketplace.tf

https://marketplace.tf/items/380;5;u35

https://backpack.tf/item/1571039585

27/2.03 = ~13.3

X = 13

Sale 2:

Sold for 11 keys

Seller: https://backpack.tf/profiles/76561198067575136#!/compare/1495238400/1495324800

Buyer: https://backpack.tf/profiles/76561198111475184#!/compare/1495238400/1495324800

X = 11

Sale 3:

Sold for 11 keys

http://www.tf2outpost.com/trade/29221147 ?

Seller: https://backpack.tf/profiles/76561198016530188#!/compare/1496620800/1496707200

Buyer: https://backpack.tf/profiles/76561198092229407#!/compare/1496620800/1496707200

X = 11

Sale 4:

Sold for 10 keys and 10 ref to a quickbuyer

Seller: https://backpack.tf/profiles/76561198114604882#!/compare/1497744000/1497830400

Buyer: https://backpack.tf/profiles/76561198002186909#!/compare/1497744000/1497830400

X = 10

Sale 5:

Quicksold for 10 keys + a rec

http://www.tf2outpost.com/trade/29212103 - B/O of 10

Seller: https://backpack.tf/profiles/76561198044738986#!/compare/1496448000/1496534400

Buyer: https://backpack.tf/profiles/76561198072002397#!/compare/1493856000/1496620800

X = 10

Sale 6:

Bulk for Scorching Luchadore

Seller: https://backpack.tf/profiles/76561198089330547#!/compare/1494892800/1495152000

Buyer: https://backpack.tf/profiles/76561198067575136#!/compare/1495065600/1495152000

Sale 7:

Bulk for something

Seller: https://backpack.tf/profiles/76561198111475184#!/compare/1499299200/1499472000

Buyer: https://backpack.tf/profiles/76561198375703304#!/compare/1499385600/1499472000

Sellers:

11.47 keys:

http://i.imgur.com/jTLt9zg.png - 5 days

11.5 keys:

http://i.imgur.com/dPBQfM3.png - 20 days

12 keys:

http://i.imgur.com/WyG9CKW.png - 16 days

http://i.imgur.com/bG9aSCt.png - 1 month

13 keys:

http://i.imgur.com/EK4dcHh.png - 6 days

Sales at:

10 (2x)

11 (2x)

13

Sales at 10 quicksold/went to quickbuyers. Excluding 10.

13 is an outlier, due to the mass unsolds for cheaper. Excluding 13.

Going with 11 flat.