Get a Brother machine. I've had 4 and love them all. After 6 years of hard use, one broke when it fell out of the car while we were traveling - not my happiest moment! The manuals with the Brother machines are wonderful and don't assume that you already know everything there is to know about sewing and sewing machines.
I can't say enough good things about the Brother machines I own.
One hint - if your son can find a sewing machine that cuts the thread, it is worth it. I don't know how I ever sewed without having that feature!