Sale 1:

Sold for 16 keys

http://www.tf2outpost.com/trade/28826179 - No B/O

Seller: https://backpack.tf/profiles/76561198192602363#!/compare/1489536000/1489622400

Buyer: https://backpack.tf/profiles/76561198128321923#!/compare/1489536000/1489622400

X = 16

Sale 2:

Sold for 16 keys

User doesn’t list B/O’s on outpost, no point checking there.

Seller: https://backpack.tf/profiles/76561198011321852#!/compare/1492300800/1492387200

Buyer: https://backpack.tf/profiles/76561198343112612#!/compare/1492128000/1492473600

X = 16

Sale 3:

Sold with cheap cosmetics for Australium Flamethrower (15 at the time) in ~1 day

http://www.tf2outpost.com/trade/28843364 - B/O of 15

Seller: https://backpack.tf/profiles/76561198328210524#!/compare/1490140800/1490227200

Buyer: https://backpack.tf/profiles/76561198117542709#!/compare/1490140800/1490227200

X = 15

Sale 4:

Quicksold for 14 keys

http://www.tf2outpost.com/trade/28835246 - B/O of 14

Seller: https://backpack.tf/profiles/76561198043505317#!/compare/1489708800/1489795200

Buyer: https://backpack.tf/profiles/76561198043998729#!/compare/1489622400/1489795200

X = 14

Sale 5:

Sold with 2 keys + ~1 key in metal for Blizzardy Fukaa

Seller: https://backpack.tf/profiles/76561198043998729#!/compare/1490054400/1490227200

Buyer: https://backpack.tf/profiles/76561198328210524#!/compare/1490140800/1490227200

Should be used on the Fukaa.

Sellers:

14 keys:

http://i.imgur.com/3aC8lvz.png - 9 days, owns two, one of them purchased ~40 days ago:

https://backpack.tf/item/501792615 (~10 days)

https://backpack.tf/item/924819406 (~40 days)

https://backpack.tf/u/76561198344491537

16 keys:

http://i.imgur.com/fO4RmPM.png - 3 months

https://backpack.tf/u/76561198012613726

http://www.tf2outpost.com/trade/28822463

Sales at:

14

15

16

Would normally exclude 14 and 15 given the sales, however, both sales were over 2 month ago, and there is now an aged seller at 14. Therefore, keeping 14 and 15 in the range.

Going with 14-16.