Unlike most LP releases, they do have collector value, especially since
they are sealed. I'd suggest you auction them at eBay. The performances
are available more or less readily on 'private' labels, but the sets are
beautifully prepared. Originally, they were offered as 'gifts' for
donations of about $150 each. They may bring a significant fraction of
that amount today. I'd suggest a minimum bid of the order of $50 each.