I think I wont sell lasers I tired to sell one to a 40 year old who with in 5 sec of having it in hand shined it at me, at his dog, and cars, AFTER I GAVE HIM A SAFETY BRIEFING, I almost punched him. Any way you got a point you can't say your responsible because your 50 but if you sell a laser to an adult and he hurts someone, his problem. If you sell to a minor and he hurts himself or someone, your problem and lawsuit. My 2c if you sell a diode and the minor makes a laser well good from him, unless he or she is 4 and chokes on the diode.
AS far as I know, you should not openly sell lasers in the US unless they meet code, and we all know most don't. You can sell a kit and they can't do anything....yet.