Sale 1:

Sold for 12 keys + ~20 ref in items

http://www.tf2outpost.com/trade/29380220 - B/O of 13

Seller: https://backpack.tf/profiles/76561198107829703#!/compare/1506211200/1506297600

Buyer: https://backpack.tf/profiles/76561198145512675#!/compare/1506297600/1506384000

X = 13

Sale 2:

Sold for 10 keys + Bill’s (~2)

No outpost

Seller: https://backpack.tf/profiles/76561198251995154#!/compare/1503446400/1503532800

Buyer: https://backpack.tf/profiles/76561198105928538#!/compare/1503446400/1503532800

X = 12

Sale 3:

Sold for 11 keys + ~0.5 keys in metal

http://www.tf2outpost.com/trade/29354519 - B/O of ~11.5

Seller: https://backpack.tf/profiles/76561198045692488#!/compare/1504483200/1504569600

Buyer: https://backpack.tf/profiles/76561198065594634#!/compare/1504224000/1504569600

X = 12

Sale 4:

Sold for 12 keys (IDs match)

http://www.tf2outpost.com/trade/29376096 - B/O of 14, seller confirms sale

Seller: https://backpack.tf/profiles/76561198364468892#!/compare/1505952000/1506038400

Buyer: https://backpack.tf/profiles/76561198047401076#!/compare/1505952000/1506038400

X = 12

Sale 5:

Sold for 11 keys + 6 ref

No outpost

Seller: https://backpack.tf/profiles/76561198304138933#!/compare/1505433600/1505520000

Buyer: https://backpack.tf/profiles/76561198260896310#!/compare/1505174400/1505520000

X = 11

Should be used on the Blizzy.

Sale 6:

Quicksold for 10 keys + ~0.5 keys in items

Seller: https://backpack.tf/profiles/76561198042663181#!/compare/1506124800/1506211200

Buyer: https://backpack.tf/profiles/76561198061747040#!/compare/1506124800/1506211200

X = 11

Sale 7:

Bulk for Terror-Watt Boxcar

Seller: https://backpack.tf/profiles/76561198159690821#!/compare/1502928000/1503014400

Buyer: https://backpack.tf/profiles/76561198162282453#!/compare/1502928000/1503014400

Sale 8:

Sold with 8 keys and a skin for Blizzardy Storm Defiant Spartan

Seller: https://backpack.tf/profiles/76561198260896310#!/compare/1505520000/1505606400

Buyer: https://backpack.tf/profiles/76561198158206236#!/compare/1505520000/1505606400

Should be used on the Spartan.

Sale 9:

Bulk for pure

Seller: https://backpack.tf/profiles/76561198227733640#!/compare/1503792000/1503878400

Buyer: https://backpack.tf/profiles/76561198341086501#!/compare/1503792000/1503878400

Sale 10:

Sold for Steaming Bonk Leadwear + < 0.5 keys in items

Seller: https://backpack.tf/profiles/76561198341086501#!/compare/1503964800/1504051200

Buyer: https://backpack.tf/profiles/76561198298857424#!/compare/1503964800/1504051200

Not many sales on the Leadwear, would prefer to use it on that instead.

Sale 11:

Sold for Bubbling Stainless Pot

http://www.tf2outpost.com/trade/29341626 - B/O of ~11.4

Seller: https://backpack.tf/profiles/76561198040224815#!/compare/1503446400/1503532800

Buyer: https://backpack.tf/profiles/76561198251995154#!/compare/1503446400/1503532800

Can be used on the pot.

Sale 12:

Sold for Miami Nights Broadband Bonnet

Seller: https://backpack.tf/profiles/76561198145512675#!/compare/1506384000/1506470400

Buyer: https://backpack.tf/profiles/76561198034462711#!/compare/1506038400/1506470400

Can be used on the Bonnet.

Sellers:

11 keys:

https://i.imgur.com/Nlruwnb.png - 4 days

Sales at:

11 (2x)

12 (3x)

13

The quicksale at 11 was not for a full 11 keys. Given that, and the current seller at 11, I will not exclude 11.

Going with 11-13.