you can add everything up including ingredients, overhead and papertowels, hot water, soap and time to wash the dishes, then add on for your profit, and your hourly wage, and gas and time to drive to all the stores to purchase all the supplies yada yada yada
if it's a once in a while i'd go with the first idea
did you mean an eight foot cake??
one baker's never ever do is the next baker's 'i swear by this'