Hi, I work with a nonprofit and we were recently left a "seemingly old" Bachmann Electric Train Set.  It has two NW engines #s 8824 and 8825, 5 cars and a caboose. 

How do I know how much it is worth/and or what to do with it?  The part number on the box is AF 33-7834-2.  No date or other title that I could find. 

Thanks for your help!

K