Competing Bids on Body Work (for the rental car I dinged)

I recently went on a trip where I backed the rental car into a pole.  The bumper had some paint on it but the car was totally driveable.  They charged me $240 to fix the bumper and even after I called to complain about the price they were only able to lower the cost to $135.  All they had to do was buff off some paint.  It would be nice to have a second opinion body shop close to the airport that could rush in and give a bid on the damage you've done.  Now we are held hostage by whatever the rental car company sets the price at.  Who knows maybe they could fill in work by repairing planes when they hit birds.  Or even better, do custom paint jobs on the planes and rental cars.