I have only done this cake one time and the first time it was a gift
now someone else wants it
It is 10 inch square & 8 inch round
How much wold you charge?
Is it buttercream or fondant? Do you have a pic of it?
Depending on the flavors I would charge at least $55 extra if multiple colors and fondant decorations.
Maybe you could figure out a price you would like to charge per serving and add extra for any additional decorations needed.