This needs a drop.

Sale #1:

Offered and sold for a Smoking Hot Dogger:

http://www.tf2outpost.com/trade/26451037

History of the Head Warmer:

http://backpack.tf/item/2625693105

History of the Hot Dogger:

http://backpack.tf/item/1349796766

Seller's backpack after:

http://backpack.tf/profiles/76561198138707710?time=1436692725

Total: 13 keys (no overpay applied as Head Warmer was offered)

Sale #2:

Sold for a Blizzardy Storm Demoman's Fro:

http://www.tf2outpost.com/trade/26327819

Seller's backpack after: http://backpack.tf/profiles/76561198108511797?time=1436188614

Buyer's backpack after: http://backpack.tf/profiles/76561197968572087?time=1436201212

History of the Head Warmer: http://backpack.tf/item/1387913088

History of the Fro: http://backpack.tf/item/1107296550

Total: 19*0.9 = 17.1 keys

Rounding it down to 17 keys

Please tell me if I did anything wrong.