4 months outdated.

Sale #1

http://www.tf2outpost.com/trade/18930490

http://www.tf2outpost.com/trade/18741837

Sold for Lucky Shot Nuts n Bolts(15.5 keys)

Backpack of seller

http://backpack.tf/profiles/76561198055222756?time=1397718000 Before

http://backpack.tf/profiles/76561198055222756?time=1398150000 After

Backpack of buyer

http://backpack.tf/profiles/76561198104898708?time=1397977200 before

http://backpack.tf/profiles/76561198104898708?time=1398066172 After

Total: ~16 keys

Sale #2(Calling this an outlier)

http://www.tf2outpost.com/trade/19450058

Sold for Strange Killstreak Festive Huntsman with Headshot kills (~12 keys)

Backpack of seller

http://backpack.tf/profiles/76561198129737110?time=1398460829 Before

http://backpack.tf/profiles/76561198129737110?time=1398754800 After

Backpack of buyer

http://backpack.tf/profiles/76561198041401847?time=1398409200 Before

http://backpack.tf/profiles/76561198041401847?time=1398528180 After

Total: ~12 keys

Sale #3

http://www.tf2outpost.com/trade/19545406

Sold for Trencher's Topper Steaming(16.5 * 0.9 = ~15 keys) + 2 keys

Backpack of seller

http://backpack.tf/profiles/76561198041401847?time=1399964400 Before

http://backpack.tf/profiles/76561198041401847?time=1400050800 After

Backpack of buyer

Unable to provide backpack history of before.

http://backpack.tf/profiles/76561198134841829?time=1400123975 After

Total: ~17 keys