Perhaps the range is too big?

Sale 1

http://www.tf2outpost.com/trade/26037085 Sold for Glory Wraith + Flies Counter + 7 keys

B/O for Wraith was 165

Danger had no trade, but wasn't offered

X = 115*0.9 + 7 + 11*0.9

X = 120

Danger http://backpack.tf/item/3161172955

Counter http://backpack.tf/item/2912366400

Wraith http://backpack.tf/item/3271371663

Mini for Counter

http://www.tf2outpost.com/trade/26221272 "Quickselling" for 11, using 11

Mini for Wraith

http://backpack.tf/vote/id/5594bc17b98d886e678b4568 115, using 115

Sale 2

http://www.tf2outpost.com/trade/26137149 Sold for Shadows Private + Frostbite Whirly

B/O for Danger was 175 keys

Private and Whirly had no trade, presuming offered

X = 59*0.9 + 79.5*0.9

X = 125

Whirly http://backpack.tf/item/3377628490

Private http://backpack.tf/item/2047291046

Danger http://backpack.tf/item/3161172955

Mini for Private

http://www.tf2outpost.com/trade/25604102 Sold for 2 Flies Racks

X = 33*0.9 + 33*0.9

X = 59

Rack 1 http://backpack.tf/item/3591541106

Rack 2 http://backpack.tf/item/919937030

Private http://backpack.tf/item/2047291046

Sale 3

http://www.tf2outpost.com/trade/25770381 Sold for Demonflame Bubble + Pro KS S. Ax

B/O for Danger was 180

X = 100.5*0.9 + 2*0.9

X = 92

Ax http://backpack.tf/item/748607441

Bubble http://backpack.tf/item/2076429310

Danger http://backpack.tf/item/3161172955