depends what your market is.... here in san diego its buy junk make it look and run like a jewel and sell it high.... i've seen plenty of cars here that guys put about 5k into it and sell it for about 35-40k..... we have a good market here.... i make more money doing it than i do working in the shop, but i'm saving up to start my own hotrod shop.... one of the cars i did was a 62 mercury monterey found it in the junkyard paid $500 for the car with a straight body... redid the intererior and paint for 4k cleaned the motor up and put a new carb on it, sold it for 26k