Very expensive hobby.  I bought a Diamond Jubilee set with minimal track for about $500 a few months back. I am scared to put together because I know that it will never stop expanding once you get the bug. I saw a personality on TV once where her husband had tracks running through every room of the house.
In your case, the value needs to be assessed on each individual component by an expert. You may find some valuable gold nuggets in there somewhere. One locomotive or carriage could be worth $50 where a rare one could be several thousand dollars.