I charge $3 a serving for American BC, $4 a serving for SMBC and $5 a serving for fondant. I know prices vary from place to place. Supplies are expensive up here, most my customers still order fondant cause they like the look, glad to cause I prefer working with fondant over the other two buttecreams. I understand why people would charge the same for buttercream and fondant, I too push the fondant cakes.
Jessica, Kodiak Alaska http://www.facebook.com/ConceptualConfections