This explains a lot. I wrote a small book back in the 90s that had few sales and was unlamented when it fell out of print. A couple of years ago saw it as the subject of an amazon.com sidebar ad and was astonished to find that it was listed at $100 or thereabouts, and couldn't imagine how or why it might have become collectible. The idea that this was the result of competing pricing algorithms makes a great deal more sense to me.

Now, if you'll excuse me I'm off to weep over my broken dreams of belated celebrity.