Check with your local HD because you may need a separate wholesale license.
When I wholesale, and I do quite a bit, I only adjust by the time savings. For example, if it is a large volume of the same item, the time savings of doing the same item is all that I will discount. I make the same amount personally whether I retail or wholesale. After you get into the routine, the wholesale beciomes more profitable.
I do not ever work for less than my personal per hour price.
When looking at market price, remember this is for a premium, from scratch item. Even Starbucks does not have this, so be aware that market price may be above the highest prices currently available. Don't undersell yourself.