Sale 1 : http://www.tf2outpost.com/trade/26128881

Before : http://backpack.tf/profiles/76561198046652234?time=1432710000

After : http://backpack.tf/profiles/76561198046652234?time=1433746800

Sold for a Death at Dusk Carouser's Capotain ( 30 keys ) but 10 were added : ( 30 * 0.9 ) - 10 = 17 keys.

Sale 2 : http://www.tf2outpost.com/trade/25810829

Before : http://backpack.tf/profiles/76561198026705994?time=1430204400

After : http://backpack.tf/profiles/76561198026705994?time=1430290800

Sold for a max : 25 keys

Sale 3 :

Before : http://backpack.tf/profiles/76561198007437847?time=1436252400

After : http://backpack.tf/profiles/76561198007437847?time=1436684400

Sold for 12 keys (outlier)

Sale 4 : http://www.tf2outpost.com/trade/25907432

Before : http://backpack.tf/profiles/76561198053796001?time=1432882800

After : http://backpack.tf/profiles/76561198053796001?time=1432969200

Sold for a Miami Nights Outdoorsman : 23 * 0.9 = 21 keys

Sale 5 : http://www.tf2outpost.com/trade/25942175

Before : http://backpack.tf/profiles/76561198086846963?time=1431500400

After : http://backpack.tf/profiles/76561198086846963?time=1431586800

Sold for a Stormy Storm Sergeant's Drill Hat : 20 * 0.9 = 18 keys

thus taking the range of 17 to 25 keys.

Supportive criticism welcome