I charge $3 per serving for buttercream so for me it would be $45. Actually $50 since I have a minimum order amount. $4 for fondant.
I have a base price of 45.00. How much did it cost you for ingredients and how much do you want for your time. Cake decorating is a hobby for me so I usually charge 25.00 to 30.00 for my time plus ingredients.