Flight sims are good. It helps train your fingers. I didnt care for them at first cause it didnt seem that realistic. But now I see a definate bennifit based on people that have used it, then came to me for training. They advanced faster than those starting from ground 0. Your son will love it, and I hope he sticks with it. You should learn too if your interested. Our club prez and his son (14 now) both fly. The kid flys giant scale aerobatic and is pretty good. He started I think around age 9 or so. This is one of those hobbies that can be as cheap as you want, or as expensive as you want.
Edwin