How bad is your paint? I would look into having your paint restored before doing anything else. With some clay and a good buffing, you could probably make the paint look decent. Forget about painting it - would cost at least 2 grand to get something quality.
I would advise you to keep your car, rather than sell it. I had to make the same decision, and decided to keep my car. I have a lot of money invested in it, and if you buy another used car, you are still going to have problems, just a new set. Why not see if you can get 300K outta her, then make a decision. Its not like its gonna depreciate any further with that much mileage anyways. Good luck, Mike.