I have an old Bachmann 137 piece train set that has never been opened. I am trying to figure out how to discover its value. I have attempted to search Ebay, but can't seem to find anything. I was given this new as a child and now I'm trying to decide if it is better to keep unopened or open it for my child and put the set together.

The Set: Bachmann King of the Rail Series: Rail Blazer Giant 137 Piece Train Set

Any info helps, thanks!