sale 1: sold for 13 keys

http://backpack.tf/profiles/76561198045855609?time=1429599600

http://backpack.tf/profiles/76561198045855609?time=1429772400

sale 2: sold for miami nights tavish[14 keys via mini]

http://backpack.tf/profiles/76561198089564999?time=1431327600

http://backpack.tf/profiles/76561198089564999?time=1431500400

14*0.9=12.6 rounding to 13

sale 3: sold for eerie orbiting fire buckaroo[16 keys]

http://backpack.tf/profiles/76561198089564999?time=1432796400

http://backpack.tf/profiles/76561198089564999?time=1433574000

16*0.9=14.4 rounding to 14

sale 4: sold with a bills[2 keys] for planets prussian[17 keys via mini]

http://backpack.tf/profiles/76561198093819043?time=1433487600

http://backpack.tf/profiles/76561198093819043?time=1433574000

17-2=15

mini on tavish: sold for logo gonzilla[14 keys via mini]

http://backpack.tf/profiles/76561198038823313?time=1431586800

http://backpack.tf/profiles/76561198038823313?time=1431759600

mini on gonzilla: seller at 14 keys

http://www.tf2outpost.com/trade/26224893

mini on prussian: sold for g.fetti prussian[16.5 keys]+lime s.aspect[2 keys including paint]

http://backpack.tf/profiles/76561198093373622?time=1433660400

http://backpack.tf/profiles/76561198093373622?time=1434006000

16.5+2=18.5

18.5*0.9=16.65 rounding to 17

sales are at 13, 13, 14, and 15.

taking final price as 13-15 keys.