You didn't add in the time to clean up. For cost you should add something for equipment. Personally I think the market is limited, so I decided to not take anymore orders. I only decorate for fun, practice or love. My time is too valuable to discount my cookies and I don't think non-decorators appreciate the effort. My decision wasnt exclusively cost and time. I did a lot of cookies for a charity the year before and my shoulder paid the price.