I'm not sure but thanks for the info :-)

If they are the shiny/glossy "flashlight" yellowspine editions (like were available at Costco for a couple of years) they are not collectible and you will be lucky to get $1 each for them. Older, Matte Yellowspine editions can be collectible and are worth more $dollars depending on age and condition. If you have blue tweed editions without dustjackets, $1-$2 per book, but certain books can be worth more, depending again, on their age and condition. If you have dustjackets on the books the prices jump up considerably!! The publishing dates inside the books are not a good judge for when they were made. They might say the date is 1938 or 1959..but the glossy flashlight editions were made recently, it just means the story is from 1938 or 1959 or whatever...

-Amanda from Seattle