Officially, cellulose isn't available to the public anymore. It is still available to the trade.
Professional car repairers do use two pack paint involving isocyanite (sp) these days and have to wear breathing apparatus to do so. The work is usually done in a spray booth to allow the gas to be sucked out and to make sure the working environment is dust free.
You probably wouldn't want to do your boat in a metallic or fluorescent colour on cost grounds. I had a car done in fluorescent and the paint was £800. Labour and other materials were on top of that and it had to be baked in an oven.