Sale 1:

Sold for $27.03 on Marketplace.tf

https://marketplace.tf/items/182;5;u35

https://backpack.tf/item/843001979

27.03/2.07 = ~13.1

X = 13

Sale 2:

Sold for $26.50 on Marketplace.tf

https://marketplace.tf/items/182;5;u35

https://backpack.tf/item/472282992

26.5/2.07 = ~12.8

X = 13

Sale 3:

Sold with <1 key in items for Voltaic Hat Protector Head Full of Hot Air (13.5)

No outpost

Seller: https://backpack.tf/profiles/76561198080458927#!/compare/1498003200/1498262400

Buyer: https://backpack.tf/profiles/76561198230687132#!/compare/1497916800/1498003200

X = 13

Sale 4:

Quicksold for 10 keys + ~1 key in metal/items

No outpost

Seller: https://backpack.tf/profiles/76561198072491439#!/compare/1497312000/1497398400

Buyer: https://backpack.tf/profiles/76561198313818431#!/compare/1497225600/1497398400

X = 11

Sale 5:

Sold for Green Confetti Elf Esteem + 5 keys

No outpost

Seller: https://backpack.tf/profiles/76561198069559160#!/compare/1495411200/1495497600

Buyer: https://backpack.tf/profiles/76561198271111205#!/compare/1494460800/1495584000

Not using this sale, as the B/O would make the sale much lower. Without it, it’ll just be an outlier.

Sellers:

12 keys:

http://i.imgur.com/rhoQ6o2.png - 10 days

Sales at:

11

13 (3x)

Aged seller at 12.

Going with 12-13.