MUSIC AN PLAZZA

I'm trying to help a friend who almost sold these tapes for $2.00 each at a yard sale. She was alerted by a yard sale shopper to the value of the tapes being significantly higher than $2.00 each, which was really quite thoughtful and honest of that person. Since then, I've been trying to find information on the Internet, but nothing has led me to what a CURRENT MARKET VALUE is for the tapes. The tapes are Black Diamond Classics, and are in the original clamshell cases with the Black Diamond insignia on the spine. One of the tapes is "101 Dalmations", and the other is "Beauty and the Beast". They are both non-rentals, have been owned and viewed carefully by one owner since being purchsed and are in excellent condition. I would really like to help this friend get the highest possible offer on the tapes as she can really use the money. Any helpful answers are EXTREMELY APPRECIATED!!!