^ actually, they make more money commercially, becuase with more advertising, more people buy your shit... you need to spend money to make money... if only the whole world would realise that canibus, royce da 5'9, ras kass, and all the other great underground rappers were better than nelly, than maybe they wouldnt even need to be called "underground"

and yes, if you make your own beats and do your own production and own your own (lol) label, you'll obviously make more money depending on how successful you are. But it's probably better to mix up producers on an album so it doesnt sound the same all the way through.