Sale #1:

http://www.tf2outpost.com/trade/25318980

Sold recently for GE Brainiac+7 buds

11.2*0.9+7=17.1

Sale #2

http://www.tf2outpost.com/trade/25093049

Sold for Scorching Pyromancer(16.6), a bud(1), australium frontier(1.1)+ 2 keys in sweets(0.15)

1.25*0.9=1.125 rounded to 1.1

16.6*0.9=14.94 rounded to 15

1.1+1+15=17.1

Sale #3: outlier

http://www.tf2outpost.com/trade/24797371

Sold along with aussie prof ks grenade+aussie sticky(1.65) for scorching pyromancer

MINI FOR PYROMANCER:

http://www.tf2outpost.com/trade/24323181 - Sold for beams bonk boy

18.4*0.9=16.56 rounded up to 16.6

MINI FOR AUSSIE PROF KS GRENADE:

http://steamcommunity.com/market/listings/440/Strange%20Professional%20Killstreak%20Australium%20Grenade%20Launcher - recently sold for 80$, buds are 22$ makes it be 3.6363636364 rounded down to 3.6 buds

16.6(mancer) -(1.65+3.6)=11.35 rounded to 11.4 i guess.

first two sales both come out at 17.1, 11.4 is obviously an outlier!