That sounds more like arbitrage than money pumping; were you ever able to buy e.g. every book in a series from the same seller over a period of time, then sell the entire collection back at a premium to the same person?
Remember there was a time before computerized inventory. A book was bought, given a price and put on a shelf. That book might go up in value. The person who priced it might not work there, or remember to re-price it among the tens of thousands of books in a store. I could buy it because I recognize it went up in value then sell it back (though to be civilized about it, not that day). Some bookstores are so large they might sell a book from their warehouse then buy it back at a profit to me over their counter. Before computerized inventory this was far from unusual or irrational. Now a computer will remember what no person could remember.
An aside: The Old Brown Coat by Lord Dunsany is a short story on this topic.
Imperfect information perhaps. Selling something to the former owner the next day for (if memory serves) fifteen times what I paid for it isn’t a razor thin margin.
That sounds more like arbitrage than money pumping; were you ever able to buy e.g. every book in a series from the same seller over a period of time, then sell the entire collection back at a premium to the same person?
A series, no. A single book, yes!
Were there unusual circumstances, or was the seller just irrational?
Remember there was a time before computerized inventory. A book was bought, given a price and put on a shelf. That book might go up in value. The person who priced it might not work there, or remember to re-price it among the tens of thousands of books in a store. I could buy it because I recognize it went up in value then sell it back (though to be civilized about it, not that day). Some bookstores are so large they might sell a book from their warehouse then buy it back at a profit to me over their counter. Before computerized inventory this was far from unusual or irrational. Now a computer will remember what no person could remember.
An aside: The Old Brown Coat by Lord Dunsany is a short story on this topic.
That sounds like arbitrage combined with razor thin margins and imperfect information;
Imperfect information perhaps. Selling something to the former owner the next day for (if memory serves) fifteen times what I paid for it isn’t a razor thin margin.
Even then, the reason this happens might be plausibly explained by the changing information of the bookstore rather than actual intransitivity.