Unfortunately, It's a large range

Sale 1

http://www.tf2outpost.com/trade/26606133 Sold for 27 keys

B/O for Softcap was 32

Had been attempting to sell for a while

X = 27

Keys https://gyazo.com/9f10052c2f8ccd1e0c100b4c3e990b4b http://backpack.tf/profiles/76561198073104552?time=1438153200&compare=1438326000

Softcap https://backpack.tf/item/674490477

Sale 2

http://www.tf2outpost.com/trade/27025603 Sold for a Lev 1 Max

B/O for Softcap was 35

X = 28*0.9

X = 25

Max https://backpack.tf/item/75077952

Softcap https://backpack.tf/item/478553273

Sale 3

http://www.tf2outpost.com/trade/27007652 Sold for PE Larrikin

B/O for Softcap was 35

B/O for Larrikin was 35

X = 35*0.9

X = 32

Larrikin https://backpack.tf/item/281062279

Softcap https://backpack.tf/item/478553273

Mini for Larrikin

https://backpack.tf/vote/id/56162862ba8d88892aa41cd1 It would be 38 keys, but the B/O in the trade above was 35

Sale 4

http://www.tf2outpost.com/trade/26955126 Sold for Twatt Cowl + Pro KS S. Sniper + 1.2 keys in sweets

B/O for Softcap was 40

B/O for Cowl was 26

X = 9.7*0.9 + 26*0.9 + 1.2*0.9

X = 33

Sniper https://backpack.tf/item/2156495177

Cowl https://backpack.tf/item/1770775234

Softcap https://backpack.tf/item/478553273