Yes, there are lots of folks who really appreciate those guns. I have one passed on to me by a family member as well. I don't shoot it terribly often, but it is a fantastic gun for many uses.
How is it that you feel the need to get rid of it? Can you not see a time when you would appreciate the gun for what it is (a fast, light, easy to shoot and very capable defensive carbine which is also nearly perfect for instructing smaller statured shooters), or for the historic value, or for the tie to your grandfather?
While there were a lot of M1 Carbines produced, they are becoming more scarce all the time and the prices are increasing. Selling a quality firearm that was passed down to you is almost always a negative thing in the end. Lots of regret and little benefit.
What will you do with the $500-600 you might get for it -- what, that will give you a useful weapon, a good trainer, a piece of history, and a connection with your grandpa?
-Sam