I have just uploaded a model of a creamic mug, it was 96cm3 and a bit pricy. As I think I'd over engineered it a bit I remodelled it at the same size but with a thinner wall (now at the recommended 3mm down from 4mm). It is now 77cm3 so I expected it to be cheaper, but is actually 3€ more expensive, how can that be?
Ceramic is a little different in the pricing - they base it off of surface area instead of volume. It is likely that thinning the walls made your model have more surface area on the inside. www.bradykineticcuriosities.com
A good head and a good heart are always a formidable combination.