Sale 1:

Sold for 18 keys

http://www.tf2outpost.com/trade/28066382 - B/O of 18

Seller: http://backpack.tf/profiles/76561198021055079#!/compare/1461024000/1461110400

Buyer: http://backpack.tf/profiles/76561197967929435#!/compare/1461024000/1461110400

http://puu.sh/pIC7c/0aec17fe99.png

http://puu.sh/pIC9x/4990f72912.jpg

X = 18

Sale 2:

Sold with Strange Killstreak Huntsman (5) with ~6 keys in parts for Disco Beat Down Conquistador (19.5)

No outpost

Seller: http://backpack.tf/profiles/76561198176117759#!/compare/1464739200/1464912000

Buyer: http://backpack.tf/profiles/76561198153088409#!/compare/1464825600/1464912000

X + 5 = 19.5

X = 15 (rounded from 14.5)

Sale 3:

Sold for 14 keys

http://www.tf2outpost.com/trade/28281242 - B/O of 14

Seller: http://backpack.tf/profiles/76561198043914474#!/compare/1466812800/1466899200

Buyer: http://backpack.tf/profiles/76561198006199030#!/compare/1464739200/1466985600

X = 14

Sale 4:

Sold for 11 keys + ~3 keys in items

No outpost

Seller: http://backpack.tf/profiles/76561198093998184#!/compare/1464825600/1464912000

Buyer: http://backpack.tf/profiles/76561198058423925#!/compare/1464825600/1464912000

X = 14

Sellers:

19 keys:

http://www.tf2outpost.com/trade/28203448 - 1 month

Sales at:

14

14

15

18

Not going to exclude 18, because it’s a full pure sale.

Going with 14-18