[shakethemonkey]

But a pallet of old academic books is unlikely to be composed of such books. It is probable that most of the books are worth less than the cost of shipping, and some of the books will have some value but not tremendous value. It is astonishing the number of wonderful, high quality books that can be bought on Abebooks for $1.

[jacobolus]

Did you look at the picture? https://i.imgur.com/0qiTKSQ.jpg Books I commonly buy secondhand that look roughly like those pictured are anywhere from $10–$200 each (depending on how common the particular book/edition is); we’re talking about pretty ordinary old academic books, nothing fancy or extremely rare. A pallet of books is ~500–1000 books (there are maybe 400 in the picture, but the blog author claims that is a "sampling").

[TheCoelacanth]

That's selection bias because you are only looking at books that you actually wanted. An average book is worth much less than a book that someone actually wants.

[jacobolus]

An average (~worthless) book is something like a pulp romance novel, political book by a sitting politician, self-help guide, .... These are printed in the millions and used copies can typically be found for $1–$5 + shipping costs. That’s not the same kind of books primarily shown/described here.

Any scholarly person who loves old hardback books and spends a few decades collecting ones they personally want or need is going to end up with some worthless books, a large number that sell for $10–50 each, and a few that are worth hundreds each. It’s just inevitable, unless they go out of their way to only collect junk.

If I had to guess I’d put the price of the old man’s collection in the $10k–$30k range. But it’s plausible it could be more, if he collected anything rare.