Sale 1:

Sold for 37 keys

http://www.tf2outpost.com/trade/28389923 - B/O of 37

Seller: http://backpack.tf/profiles/76561198056531196#!/compare/1470182400/1470268800

Buyer: http://backpack.tf/profiles/76561198162796817#!/compare/1470009600/1470268800

X = 37

Sale 2:

Sold for 37 keys

http://www.tf2outpost.com/trade/28452312 - B/O of 37

Seller: http://backpack.tf/profiles/76561198021055079#!/compare/1472515200/1472601600

Buyer: http://backpack.tf/profiles/76561198131129970#!/compare/1472256000/1472601600

http://i.imgur.com/NYrxVYn.png

http://i.imgur.com/XGFNJqd.png

X = 37

Sale 3:

Sold for Orbiting Fire Human Cannonball (Mini at 20 below) + 12 keys

No outpost

Seller: http://backpack.tf/profiles/76561198162796817#!/compare/1472256000/1472342400

Buyer: http://backpack.tf/profiles/76561198021055079#!/compare/1472256000/1472342400

http://i.imgur.com/0kz9SUR.png

http://i.imgur.com/UsCe6lA.jpg

http://i.imgur.com/AJcMOsz.jpg

X = 32

Orbiting Fire Human Cannonball:

http://backpack.tf/suggestion/57df50af83de6b03ea1e5da5

Sellers:

37 keys:

http://i.imgur.com/8Srthze.png

http://backpack.tf/u/76561198131129970

Sales at:

32

37 (2x)

Due to both sales at 37 being full pure, and having sold in a short time, it would be best to exclude 32.

Going with 37