Sale 1:

Sold for Stormy Storm Bonk Helm (16)

No outpost

Seller: https://backpack.tf/profiles/76561198181076763#!/compare/1498089600/1498176000

Buyer: https://backpack.tf/profiles/76561198087169198#!/compare/1498003200/1498176000

X = 16

Sale 2:

Sold for $29.01 on Marketplace.tf

https://marketplace.tf/items/626;5;u35

https://backpack.tf/item/1366567221

29.01/2.05 = ~14.2

X = 14

Sale 3:

Sold for 12 keys + 7 ref

Seller: https://backpack.tf/profiles/76561198304138933#!/compare/1496275200/1496361600

Buyer: https://backpack.tf/profiles/76561198255714618#!/compare/1496361600/1496448000

X = 12

Sale 4:

Sold for 12 keys

http://www.tf2outpost.com/trade/28860400 - Nothing cached

Seller: https://backpack.tf/profiles/76561198106233311#!/compare/1496620800/1496707200

Buyer: https://backpack.tf/profiles/76561198128228072#!/compare/1496534400/1496707200

X = 12

Sale 5:

Sold with 4 keys for Smoking Killer’s Kabuto (18.5)

No outpost

Seller: https://backpack.tf/profiles/76561198098880809#!/compare/1494115200/1494720000

Buyer: https://backpack.tf/profiles/76561198121021107#!/compare/1494633600/1494720000

https://backpack.tf/suggestion/596e3d84cf6c753b5e0c5d13

(Refer to the comment on sale 14)

Not gonna get an exact price from this sale as it’s rather bulky. Will use it to support the marketplace sale at 14, however.

Sale 6:

Bulk for Peace Sign Tyrants

Seller: https://backpack.tf/profiles/76561197974225531#!/compare/1497744000/1497916800

Buyer: https://backpack.tf/profiles/76561198272062150#!/compare/1497744000/1497916800

Sellers:

13 keys:

http://i.imgur.com/fJxQ7LJ.png - 17 days

Sales at:

12 (2x)

14

16

Supportive sale at 14.

16 looks like an outlier, given the current seller and the sales at lower. Excluding 16.

Aged seller at 13.

Going with 13-14.

Cheers to Mindacos for advice on the range