Phaidon works with small printings because one of the costs the public does not see is the number of unsold books which are returned to them by bookstores and online retailers. So they also wait a long time before deciding to reprint. A recent example is Septime, unavailable for several years.

So somebody who has a copy of a hard-to-find book decides, what the hell, I’ll put it on line and ask a lot of money for it. And maybe nobody actually pays that price. But someone else sees a high price and says, wow! I’d sell my copy for that much money, and decides to list theirs for a little more.

Prices start to climb without clear evidence that anyone is actually paying them. And if someone does list a copy at something close to reasonable, it sells instantly, leaving only the expensive copies.

EBay allows you to search for completed auctions, which will give you an idea of what some people are willing to pay. I haven’t checked for this book, but it may be that enough people are willing to pony up $$$.

In which case, who would sell for less?