John, you should check the comparable prices on the finish with a reputable antique dealer. Sorry, I can't help you there.
If you do decide to remove the rust, you might check some of the industrial surface restoration places. There are processes like glass bead blasting that are a lot less abrasive than sand blasting, and tremendously less damaging that a wire brush. Is this price effective?? The answer will be determined by your pocketbook and the value of the piece.