a good paint job will be,unfortunately,around $5000.Because of that I always pay close attention to the paint when I'm buying.One of the reasons that I bought my current SLK was the immaculate paint.The other reason was a transferable warranty(and the previous owner was fastidious on maintenance).
If you have a marginal interior(seats,carpet,console,etc)that is not nearly as expensive to make new again.Plus,you can with a little effort,do a lot of the interior work yourself.
Translated,don't sweat the interior but make sure the engine,drive train and paint are as good as you can get.
later,ch7ckc