About the value I have seen these going around 200usd in ebay, but if two bidders get into a war this watch could get 250+usd.

On the other hand If I got a watch that belonged to my grandfather I would keep it and pass it on to the next generation. With a good service this watch should keep ticking for another 40 years and since the case and crystal are virtually scractchproof the watch would look good forever.