How much is my Elder book worth?

I am asked this question more often than all the other questions combined.

Most Elder titles are not worth much money. They might be old, they might be beautiful, and they might be hard to find, but this does not necessarily make them valuable. What matters most is the book’s condition. Most Elder titles, even if they’re in excellent shape, sell on Ebay for $20-40. If the book still has its dust jacket, probably a bit more. If the book came in a special gift box, probably more than that. If, on the other hand, the book is in poor condition, it might not sell at all.

A few Elder titles are particularly well-known and desirable, such as:

Many titles were issued in more than one bindings, for example, paper over boards and cloth over boards. A few, such as the individual titles in the Mosaic Essays series, were issued in as many as five different bindings. Elder also issued a large amount of ephemera, much of which is now quite rare. Catalogs, particularly ones before 1912, and copies of his in-house magazine Impressions are also in demand.

Lastly, a note on terminology: to a bookseller, “good” condition is bad thing: only “poor” condition is worse. The scale from best to worst is: fine (sometimes “mint”), near fine, very good, good, fair, poor.