I was browsing around and happened upon a book called “Big Book of Scrabblegrams”. It’s just a garden variety spiral-bound puzzle book. I found a few used ones for about $2. But then at Amazon and B&N I saw copies for several hundred dollars–for used ones! These are in no way collector’s items.
Why would pricing for something like this be so completely irrational?
From what I’ve read when the question has been asked before I believe those prices are set by automated market tracking software, not humans, and are due to algorithm imperfections/outlying input conditions/glitches/etc.
I suspect that it’s also true that some sellers deliberately set prices that are absurdly high just on the off-chance that someone will be stupid enough to buy the item at those prices.
This is what I’ve heard. It’s two automatic pricing systems chasing each others tails. Suppose some book dealer has a program that reads the prices currently being asked for a book he’s selling, figures out the average price, and then automatically sets the price of his book at five percent above the average price. No big deal.
But if two dealers are using the same program, their price increases will constantly be bumping up the average price and the rising average price will constantly be bumping up the prices they’re asking.
I wondered about this too. There are two copies of an out-of-print book of mine (published only in 2003) for sale on Amazon, one for $461.00 and the other for $2,475.00. 
This is intriguing, since the book originally sold for about $15 and I have around 10 copies sitting around. But I doubt very much I’m going to make $25,000 if I try to sell them. 
Which presumably explains the books I have bought for a few cents, automated programs trying to undercut one another. I could never figure why anyone would waste their time putting up a used book for 10 cents.
10 cents + 3.99 shipping - the high volume sellers apparently can make a buck or so on each sale (since their actual postal costs are lower) and it adds up.
I always think it’s some kind of money laundering or you can do it to take out a cash advance against your credit card. Yes it’s a VERY, VERY expensive cash advance but if you have no other options.
Credit cards often have different credit and cash advance limits. So if you have a $5,000 credit limit and a $500 cash advance limit, you simply list a book for $5,000 and buy it from yourself. Of course you’re using paypal in anther name, that you also control, but you get the idea.
You buy the book from that paypal account and move the money to yourself. Of course you’re paying fees up the wazoo, and if you get caught paypal will freeze you out but still people do it.
While the amounts are not nearly as large, I just looked on Amazon at a book I published about ten years ago. Amazon is selling it new for $57, the original price is shown as $50 and you can buy it used for only $102.21. Can anyone explain that?
It’s probably the automated price-adjustment software, mentioned already in this thread and in the post I linked to earlier.