I'm not sure what to charge for a cinderella cake, it's going to be the 3d doll cake ontop of a 14 inch round bottom cake layer.
Unless you're making a generic cake and putting store purchased Cinderella figurines on top...you charge nothing because to do so is against copyright infringement laws.
That's true only if you're copying a particular version of the Cinderella character...which after all is a traditional fairy tale. Not at all the same as, say, Spongebob or Mickey Mouse, which exist ONLY in copyrighted form.
Anyway, the doll cake pan makes approximately 10 servings. So if you normally charge per serving, there you go. Plus the cost of the doll, unless the customer is supplying one. Doing a doll cake is not really that different from doing a normal layer cake so you shouldn't need to charge a premium like you might for a custom-sculpted 3D cake.