I don't know of any high quality(restoration level) shops that will paint over any work but their own.I do know of some quality shops here that will,but no guarantee of any kind.There are guys around though that will come to your house on a weekend and squirt your car.My painting experience has been limited to painting a few hundred trucks and pieces of equipment,and maybe a hundred cars or so.Kind of like Maaco with better materials.I felt I got burned a few years ago by a man that had his 41 Ford truck ready to paint.He was disabled,and put the truck together over 15 or 20 years on nickles and dimes.The truck was a clam to start with,and when he got done with the bodywork it was quite presentable.I put some blue paint on it and it was a nice looking driver.He took the truck to local cruise nights and old home weekends for years.When lookers picked the bodywork apart he would tell them that I had painted it.He wouldn't tell anybody that he had done the bodywork,well,he would if somebody asked him outright.Where I'm not in the car painting business it never hurt me,but it could hurt guys who are in the business who paint over others work.If and when the paint peels,or the substrate shrinks and the sanding scratches in the plastic and primer jump out the paint guy gets the blame.Maaco doesn't care.when you bring in a car that you have done the prep on you get to sign a waiver of the quality of the end result.Most people I know would be happy with Maaco paint jobs.If kept under cover when parked they can look presentable for a long time.At one time the one here was using a paint called Sun Belt.It would start to fade on its way out the door.One sure thing about Maaco here,you will not see the same guy who painted your car if you come back in six months.The fresh out of body school kids will stick around for a while,they are young and can keep up the pace.There are no places left that will rent you booth space now either,unless you have a friend that owns one.The guys here tell me the insurance companies closed that door with a slam.I never saw any profit in that anyway.You have to make room,move cars out of the way,get the car in,let the guy set up,get ready,mix,paint,clean up,usually dispose of his paper and scraps,run the lights,fan,compressor,then put everything back so you can get back to work the next day,then on top of it all it has to be done after hours so you are there instead of home or doing something else.A couple hundred bucks to rent a booth out gets to be more work than it is worth.