the writer is saying that they find it interesting or crazy, that the publisher (who produces and prints books) would read a book that they didn't think it was worth publishing (producing and printing the book).

the writer is saying that they find it interesting or crazy, that the publisher (who produces and prints books) would read a book that they didn't think it was worth publishing (producing and printing the book).

It's like,..'If he didn't want to publish a that, it's amazing that anyone else would' ('should' means 'would' in this kind of old-style English! And I think worthwhile is one word..)

“That any bookseller should think it worth-while to purchase what he did not think it worthwhile to publish seems extraordinary.” From the context it seems a bookseller needs to market a book properly as well as have it ready to publish. But in this specific example, if a book seller buys something that he wouldn’t consider publishing, it seems strange as he’s buying a product he wouldn’t endorse.