Cheaper 9 mm is about 11-12 cents a shot. Reloading would be about 6-7 cents in components + time. Even on progressive manual press one could do maybe 300 rounds an hour [sustained rate]. Thus one would be saving about $15/hour by reloading 9mm for a SMG. More, that guy I mentioned would be spending an hour and a half just to reload enough ammo for his 10-15 min session.
People don't reload strictly for the price savings as your post alludes to. I do it for the hobby and to try out some funky loads.
i'd assume anyone with the money to afford a full auto, probably doesn't worry too much about ammo costs.