Sale 1:

Sold for 13 keys (Buyer’s link, one key doesn’t match)

No outpost

Seller: https://backpack.tf/profiles/76561198119563409#!/compare/1489795200/1489881600

Buyer: https://backpack.tf/profiles/76561198091419784#!/compare/1489881600/1490659200

X = 13

Sale 2:

Sold for $23 on Marketplace.tf in ~4 days

https://marketplace.tf/items/254;5;u16

https://backpack.tf/item/276412462

Buyer is unknown.

23/2.14 = ~10.7

X = 11

Sale 3:

Bulk for Pro. KS Aussie Wrench

Seller: https://backpack.tf/profiles/76561198091419784#!/compare/1492041600/1492300800

Buyer: https://backpack.tf/profiles/76561197994587943#!/compare/1491955200/1492041600

Sale 4:

Sold for Orbiting Planets Magistrate’s Mullet

http://www.tf2outpost.com/trade/29182901 - B/O of 13

Seller: https://backpack.tf/profiles/76561197994587943#!/compare/1495670400/1495756800

Buyer: https://backpack.tf/profiles/76561198137433111#!/compare/1495411200/1495756800

Was originally listed on marketplace.tf, before it got pulled.

Can be used to update the Mullet.

Sellers:

12 keys:

http://i.imgur.com/7bgNqOj.png - young-ish

https://backpack.tf/u/76561198137433111

Sales at:

11

13

Going with 11-13. (Cheers Fish for the help on the range)