Here is a review of online search and a directory of dealers . So the listings and discussion are oriented toward economics books and books about economics . Still, much of the discussion will be generally useful. Both rare and used are covered here.
Rare books are generally more valuable, of course, and so they bear greater marketing expense.
A paper catalog of rare books is often an attractive volume itself. Anyway, the books are usually described in detail, as in these example rare book listings by Robert Rubin. We have not purchased books from all the dealers listed here and we cannot generally vouch for their honesty and reliability. Of course, most sources for books do make public statements of methods, terms, and prices of purchase, but that information is not covered here, where the point is finding the book. I recommend beginning with my review of online search .