No actually I always see the single for more.
I always just figured the single was rarer (plus, since the package is basically just paper, it's harder to keep it in good condition - the auctions I saw all pretty much were). Either that or people are more interested in buying the single because maybe they had the bootleg before and want the real thing as a replacement.
I DO see the album up for auction more often, which would lead me to believe that it is, in fact, slightly more common.
When you're dealing with items THIS rare, chances are the price is not at ALL going to be based on the actual content on the disc. The amount of music on the CD has absolutely no bearing on the price; just how rare it is & how popular the artist in question is.
Take Tori Amos for example. Her singles from the album "Y Kant Tori Read" only have 1-2 songs on them, but I've seen them go for thousands of dollars. The actual "Y Kant Tori Read" album, however, goes for $500 or less. Why? Because the singles are even more rare than the album. That's just how the market works.