What is needing to be done that would jack the price up from their estimate $2k? If they are just painting over the bondoed line and smoothed rock gaurd they would have known that at estimate time. And was a engine bay paint job always in the estimate? If you are changing what you want on them, that is one thing. But if they have the car and are now changing their estimate that is another. It never hurts to get a second opinion. That being said, $5500 does not sound bad for a quality paint job with some body work having to be done. $3500 sounded real good though.