Well first off, when people get their cars repaired, they want you to turn a broken car into a working car. They will not want to order parts and then have you replace them once the parts arrive. They just want to hand a broken car to you and get a working one in return, so you would need a wholesale parts supplier. People also want their old worn out cars fixed, I see tons of people turned away from my lhs because the parts for the car they have are no longer made.