5 month old price. None on the market

Sale 1 :

Before : http://backpack.tf/profiles/76561198053401353?time=1431154800

After : http://backpack.tf/profiles/76561198053401353?time=1431241200

Sold for a kill a waat big elfin : 24 keys * 0.9 = 22 keys

Sale 2 : (outlier)

Sold for a Stormy Storm Ol' Geezer : 13 * 0.9 = 12 keys

History of Geezer - http://backpack.tf/item/1667121334

History of Cone - http://backpack.tf/item/3265291959

Mini on the Geezer :

Before : http://backpack.tf/profiles/76561198119662522?time=1428822000

After : http://backpack.tf/profiles/76561198119662522?time=1429054188

Sold for an Aces High Virtual Reality Headset : 14 * 0.9 = 13 keys

Sale 3 :

Before : http://backpack.tf/profiles/76561198069064041?time=1431154800

After : http://backpack.tf/profiles/76561198069064041?time=1431241200

Sold for a Cloud 9 Brain Bucket ( 21 keys ) but 2 keys were added : ( 21 - 2 ) * 0.9 = 17 keys

Thus taking the range of 17 to 21 keys.

Supportive criticism welcome

PS : Thx to Randy for the help :)