Sale 1:

Sold for Kill-a-Watt Detective Noir (22.5)

http://www.tf2outpost.com/trade/28334110 - B/O of 17

Seller: http://backpack.tf/profiles/76561198021055079#!/compare/1468454400/1468540800

Buyer: http://backpack.tf/profiles/76561198174785385#!/compare/1468540800/1470096000

X = 17 (Capped by B/O)

Sale 2:

Sold for 17 keys?

http://www.tf2outpost.com/trade/28338682 - No B/O

Seller: http://backpack.tf/profiles/76561198074853269#!/compare/1468540800/1468627200

Buyer: http://backpack.tf/profiles/76561198124222069#!/compare/1467849600/1468540800

X = 17

Sale 3:

Sold for 16 keys?

No outpost

Seller: http://backpack.tf/profiles/76561198244490892#!/compare/1468108800/1469750400

Buyer: http://backpack.tf/profiles/76561198154226237#!/compare/1468800000/1468972800

X = 16

Sale 4:

Sold for Orbiting Fire Pampered Pyro (15.5) + 3 keys in items

http://www.tf2outpost.com/trade/28317438 - B/O of 16

Seller: http://backpack.tf/profiles/76561198061612240#!/compare/1467676800/1467936000

Buyer: http://backpack.tf/profiles/76561198117142864#!/compare/1467849600/1468022400

X = 16 (Capped by B/O)

Sale 5:

Sold for 15 keys

http://www.tf2outpost.com/trade/28303928 - Deleted B/O

Seller: http://backpack.tf/profiles/76561198057172126#!/compare/1467417600/1467504000

Buyer: http://backpack.tf/profiles/76561198061612240#!/compare/1467072000/1467504000

X = 15

Sale 6:

Sold for Kill-a-Watt Noble Nickel Amassment of Hats

Seller: http://backpack.tf/profiles/76561198019556015#!/compare/1469145600/1469232000

Buyer: http://backpack.tf/profiles/76561198010298914#!/compare/1469145600/1469232000

Going to exclude this sale, I do remember seeing the seller on the classifieds with a B/O similar to mine. Without the B/O cap, this sale would probably end up being an outlier

Sellers:

15 keys:

http://puu.sh/qmJni/e79dfaf1ef.png

http://backpack.tf/u/76561198114367874

17 keys:

http://puu.sh/qmJpZ/562a3824a3.png

http://backpack.tf/u/76561198010298914

Sales at:

15

16 (2x)

17 (2x)

Going with 15-17