I just have a random question for all that charge per serving.... I see this on lots of websites:

My cakes start out at $3.00 per serving for buttercream and $4.00 per serving for fondant....

Now my question is -  Do you actually ever create a cake and charge JUST the 'starting price'?

sort of

if it's under a certain amount of decoration and there's no upcharge

so it would be base price plus delivery plus tax

but the price for the cake would literally be just the base price so yes (plus delivery and tax ;)

I do stick to the base price as I work in time for basic decorating and design.  I do a lot of those buttercream rosette finishes and that is just an easy peasy way to get a lot of bang out of a simple technique. If there are separate design elements in fondant or figures, or an excessive amount of piping or brush embroidery work, then there will be an increase in charge for a 'premium design.'  

But I make sure that my 'base price' is enough to cover a basic design time--it saves me the trouble of having to price out each and every cake on each small detail.