Before you go to the expense of a new paint job have you tried giving it a proper clean? Not being flippant, just asking. It's a bit of a palaver but well worth the time. Won't bore you with the famous "two bucket method" or the full detailing clean

1. Using a lambs wool mitt and car shampoo wash bodywork (Fairy Liquid contains salt and abrasives!)
2. Dry with a clean multi fibre cloth or chamois (Polyester and polyester blend towels scratch paint!)
3. Time for the detailing clay and spray to get all the road grime off. You will be amazed what this stuff picks up from the apparently clean paintwork!
4. Repeat 1 and 2!
5. Apply wax and buff to a perfect shine using a clean lint free cloth
Personally i wouldn't use a polish unless paintwork was quite old and uncared for with lots of swirl marks. Even then it would only be as a one off to recover the paint condition.
Cheers
Mark