Ok, so i decided to round these to hundreds (it just makes more sense to me)
Uncommon Costume/Hat (160 MCs):
800 QPs
Rare Costume/Hat (310 MCs):
1600 QPs
Epic Hat (490 MCs):
2600 QPs
Pet/Spaceship Mount (830 MCs):
4300 QPs
Hoverbike Mount (1340 MCs):
7000 QPs
Normal Mount (1690 MCs):
8800 QPs
I think these would be more fair (and nice looking) prices for all the cosmetics.