The Sale:

Sold for 17 keys

http://www.tf2outpost.com/trade/28613207 - B/O of 17, re-list of http://www.tf2outpost.com/trade/28533351 (~2 months total)

Seller: http://backpack.tf/profiles/76561198204709704#!/compare/1479513600/1480723200

Buyer: http://backpack.tf/profiles/76561198035485147#!/compare/1480032000/1480118400

X = 17

Sellers:

15 keys:

http://i.imgur.com/EG8tS7f.png

http://backpack.tf/u/76561198062153053

http://www.tf2outpost.com/trade/28701910 - ~9 days, poorly bumped (only 3 views at the time before this suggestion)

19 keys:

http://i.imgur.com/GW20rfi.png - 9 days

http://backpack.tf/u/76561198136883260

http://www.tf2outpost.com/trade/28681282

http://backpack.tf/u/76561198154350385

21 keys:

http://i.imgur.com/QBSgxVG.png - 1 month

http://backpack.tf/u/76561198054945991

http://www.tf2outpost.com/trade/28650513

Sales at:

17

Not sure if I should be including the seller at 15, the listing is going to disappear in a few hours, as he doesn’t appear to be re-listing.

Going with 17 flat.