Respraying cars cheaply here is done on an industrial scale, principally by Maaco. It’s cheap, but looks it.
Bikes are another realm, a niche in which you need to charge a lot to make any money at all. Rent, prep and materials add up quick. I don’t know any painters here that would accept you prepping the bike for them - they usually have their own specific process, and don’t like the customer trying to cut corners for them.