I was thinking that your son might be interested. I know that I think it's really great fun to set these systems up. This is something the client really WANTS. It does take a lot of patience to teach them how to use the systems but you're getting paid by the hour to teach them.
By the way, as far as selling the equipment goes, I'm not going to get involved with that. I think it's better to stay free and clear of providing equipment for two reasons. One .... any popular brand that you might provide can be purchased on the Internet by the end user at your prices. Two, any "Dealer Only" available equipment will always remain YOURS. No matter what goes wrong with it or is "percieved" to be wrong with it, means that YOU're going out on service calls for a very subjective item. "My speakers don't sound basey enough." "My left rear speaker is too squawky" "My woofer isn't woofy enough." That's why I offer to go with them to by THEIR equipment. When it breaks, they can bring it back to Best Buy ...... themselves. You're out of the loop and out doing the next installation. It's really great to see the smiles when you do the demos too.