Im looking at a 1990 420 sel with 90k miles. Second owner. According to the owner it has been well maintained. The interior is in excellent condition.However, being in chicago, there are rust spots on various panels of the car. The asking price is $4500. Is it worth pursuing? What would be a good offer? What would a good paint job with overall rust treatment cost? I was thinking of offering $1500. I welcome any advice.