Short answer - Screw him and move one. From my experience the clients who try and nickle and dime you are the biggest hasseles.
You have a couple options though. First, I would offer some some BS added value like on-page optimization or facebook header and see how that goes.
If that doesn;t work I would just thank him for his time, consideration, whatever and leave the line of communication open by saying something like "Ok, if your nephew has any issues or runs into any problems I'd be happy to chime in or answer any simple questions he may have".
Check back in a week or two to see if the site has been done, if not contact the business owner to see how it's going.
But my advice would be to forget about it, unless you need this gig for portfolio reasons or are hurting for cash.