On the site the price of full colour is $0.99 and the WSF is $1.50 but when I upload a model it was more expensive than WSF, is there an error in the price calculation?
VVwww.dotsan.com
Yes, the cubic centimeters after the 20th are half price if your model is "dense".
So for 64.88cm3 for instance you pay
$1.50 (startup) + 20x$1.50 (20 first cm3) + 44.88x$0.75
that is $65.16
In Sandstone it would have been $1.50+64.88x$0.99=$65.73 a little bit more expensive.