This isn't the rarest book in the world, but it only had a handful of printings in the late 60s and is notable for its numerous illustrations by a well-known book illustrator.
Copies on ebay have sold throughout the year for about 25-40 dollars in various conditions, often ex-lib. Until recently, there were a couple of listings that were way too high, one for $125 and another for close to $250 that I thought would never sell.
A week ago, all three listings (there was a somewhat beat up copy at $40) sold.
Now the only listing on the internet left is over $700 "new" on amazon, and another at 250 used.
Is someone buying these off the market to hike up the price? Why would any normal buyer spend $250 on a book with a regular price history a tenth of that?
No, the book doesn't come up THAT often, but I'd say maybe a dozen or so a year hit ebay. Is this a thing in semi-rare books, people snapping up copies to speculate and move the market?