Front or rear? Brakes are likely a mess.
The stuck brakes are likely the least of your worries. I'd see about getting a new battery in there and trying to get the engine running off an external fuel supply before making any decisions. Yes, there will be a million vacuum leaks and you will need to rebuild the carb.
If you like fixing cars and have some extra money lying around, this might be a fun project, but I think you'll find few people willing to take it.
Is his classic car also mostly rust and sitting in parts in the driveway?
If it runs, it's likely worth $500 because anything that runs is worth $500. I doubt you can get it running without spending more than $500 though. Even if it was running when it was put into storage you're in for hoses, belts, brakes, carb gaskets and float, just to begin. If it wasn't running when it was stored, you've got the original problem to deal with too.
--scott