Meh.

Sale 1

http://www.tf2outpost.com/trade/25540161 - BO of 20 keys, never sold though.

Sale 2

Before: http://backpack.tf/profiles/76561198094711975?time=1427958000

After: http://backpack.tf/profiles/76561198094711975?time=1428044663

- Sold for a Strange Frying Pan (8 keys) + Strange Killstreak Australium Tomislav (10 keys) + Team Spirit Bruiser's Bandanna (1.5 keys) (20 keys) (No overpay)

Sale 3

http://www.tf2outpost.com/trade/25553765 - Sold for a Duped Max's Head (27*0.9 = 24 keys)

Sale 4

http://www.tf2outpost.com/trade/25453038 - Sold for a Strange Specialized Killstreak Australium Flame Thrower (20 keys) + 6 keys (20*0.9 + 6 = 24 keys)

Sale 5

Before: http://backpack.tf/profiles/76561198176604118?time=1430306004

After: http://backpack.tf/profiles/76561198176604118?time=1430463600

- Sold for a Strange Australium Wrench (24*0.9 = 22 keys)

Sale 6

Before: http://backpack.tf/profiles/76561198054002248?time=1428562800

After: http://backpack.tf/profiles/76561198054002248?time=1428815849

- Sold with 6 keys in items for a Frostbite Ye Oiled Baker Boy (27 - 6*0.9 = 22 keys) (No overpay on the Frostbite Ye Oiled Baker Boy)

Feel free to counter / support my proofs