If I got a bid for my house that broke it out like that; I'd multiply the price by 75% and know that for that price the job would get to the point where finishing it is a DIY project.
When you figure what the rest of the job is worth (if you decide to agree with him), you should settle up and then close the Permit with the town. If the job gets fouled up after you left and the work was done under your name on the Permit...3 guesses who will end up explaining things.
You have no way of knowing that the GFCIs, switches, receptacles, etc. are going to be installed properly if you leave it up to someone else. IMHO, you'd be sticking your neck out and trusting it to someone else's workmanship.
