Sale 1:

Sold for 13 keys (buyer’s compare link)

No outpost

Seller: http://backpack.tf/profiles/76561198147414482#!/compare/1488326400/1488672000

Buyer: http://backpack.tf/profiles/76561198200517778#!/compare/1488585600/1488672000

X = 13

Sale 2:

Sold for 12 keys + 1 ref

http://www.tf2outpost.com/trade/28838721 - Deleted B/O

Seller: http://backpack.tf/profiles/76561198029371596#!/compare/1489968000/1490054400

Buyer: http://backpack.tf/profiles/76561198144900214#!/compare/1489881600/1490054400

X = 12

Sale 3:

Sold for 12 keys

No outpost

Seller: http://backpack.tf/profiles/76561198125791160#!/compare/1492732800/1492819200

Buyer: http://backpack.tf/profiles/76561198100322654#!/compare/1492387200/1492819200

X = 12

Sale 4:

Quicksold for 10 keys

http://www.tf2outpost.com/trade/28804593 - Deleted B/O

Seller: http://backpack.tf/profiles/76561198343505253#!/compare/1488153600/1488240000

Buyer: http://backpack.tf/profiles/76561198147414482#!/compare/1488153600/1488240000

X = 10

Sale 5:

Bulk for Kazotsky

Seller: http://backpack.tf/profiles/76561198144819017#!/compare/1491350400/1491436800

Buyer: http://backpack.tf/profiles/76561198125791160#!/compare/1491350400/1491436800

Sales at:

10

12 (2x)

13

No current sellers.

10 quicksold. Excluding 10.

Going with 12-13.