I worked as a subcontractor for ---- electric, and he told me everything i sell mark it up times three. He's been in business since the seventies. It just kinda feels a little high, but if the customer's don't complain then why not? For example, i needed a ballast that wasn't in my van, so i went to HD and got one for about twenty. He said sell it for sixty. So when it was time to bill the customer all i could think of is this guy's going to say something about it, because he must know what this thing really costs. He never said a word. So if they do say something like why are you charging me thirty dollars for a gfci, i need a good comeback. I could give them five bucks off just so they feel better.