Do you have an extra charge you add on? How do you do this?
Your per serving cost needs to incorporate the cost of the cake, fillings, fondant plus your boards and support system as well as simple embellishments. What you will up charge for are gum paste flowers, stenciling, swags, figurines, etc. HTH.
We have a completely different pricing structure for multi-tier cakes. Single tier cakes are all priced at a flat rate per size (typically starting at $2.50-3/serving), since that's how most customers who want these types of cakes are used to buying them. Multi-tier cakes start at $5-6/serving with no flat pricing. In both cases, extra decorations are priced with either a single upcharge (for something like a topper) or an increase in the per-serving price (for a decoration that is more labor intensive for larger cakes).