Resuggesting

Sale 1 :

Before : http://backpack.tf/profiles/76561198164197974?time=1427958000

After : http://backpack.tf/profiles/76561198164197974?time=1428130800

Sold for Cloud 9 Hottie's Hoodie : 26 * 0.9 = 23 keys

B/O of 16 keys : http://www.tf2outpost.com/trade/25574636

Sale 2 :

Before : http://backpack.tf/profiles/76561198060110070?time=1428908400

After : http://backpack.tf/profiles/76561198060110070?time=1428994800

Sold for a Miami Nights Full Metal Drill Hat but 4 keys were added : 25 - 4 = 21 keys

Mini on the drill hat :

Before : http://backpack.tf/profiles/76561198060110070?time=1432018800

After : http://backpack.tf/profiles/76561198060110070?time=1432191600

Sold for a Cloud 9 Big Country : 28 * 0.9 = 25 keys

Sale 3 :

Before : http://backpack.tf/profiles/76561198118382818?time=1431673200

After : http://backpack.tf/profiles/76561198118382818?time=1431759600

Sold for a Circling Peace Sign Whoopee Cap : 21 keys

Mini on the whoopee :

Before : http://backpack.tf/profiles/76561198075816743?time=1429858800

After : http://backpack.tf/profiles/76561198075816743?time=1429945200

Sold for a Cloud 9 Scotsman's Stove Pipe : 23 * 0.9 = 21 keys

Taking the range of 16 - 21 keys.

Supportive criticism welcome.

PS : Thx to aaroncsn for the help :)