Vintage Martin Alto Saxophone from 1920s-1930s?

I have a silver-plated Martin Alto Saxophone. On the bell, there is a large engraving (of a flower I believe), and it says MARTIN Hoinolchoift ELKHART IND. On the back, it says MARTIN and the model number is 57392, and it says LOW PITCH below that. I was wondering the price range for this lovely instrument? I recently had it ultrasonic-cleaned (or whatever you call it). It's in perfect working condition, and you can clearly see how old it is, due to the some of the tarnish and age spots. It's a beautiful vintage sax. :) So, prices anyone?