In my gun club [in Massachusetts, no less] there was a guy with a legally owned SMG. He would come to the range about once a month, burn through $50 [some 400 rounds] of 9mm ammo in maybe 10 or 15 minutes, and leave till his next sighting. He didn't reload, even. Shooting full auto is fun, but is on the pricey side.
That's one reason to make your own reloads. That, and it's fun.