The value of books has been much on my mind in the past few weeks. Not the cultural value of books, or their intellectual value, or the value they impart to young minds or society at large. No, just the money, ma'am. Of course, to some extent, the market value of books reflects their greater cultural value--Gutenberg Bibles being expensive for good reasons. Oftentimes, though, market value reflects purchasing trends or societal fads--first editions of Harry Potter books, for example, are expensive for different reasons than incunabula.
Establishing a market value for old and/or rare volumes is the province of certified appraisers, and I always urge people who ask my advice on such matters to get themselves qualified help. When appraisers aren't an option and one just wants a sense of the approximate value of a given title, one can turn to some great resources on the web. Since I myself have been using a few of these sites heavily of late--and since this is the season of sharing--I share three musts and a handy below:
For trustworthiness in matters of market value, certified appraisers can't be beat. Happily, many of them list their current stocks on the International League of Antiquarian Booksellers' web site here.
Because not all reputable dealers belong to ILAB, you can also find great information on book values from viaLibri, a free site that provides cross-site searching of 18 online sales catalogs of rare and used books, as well as individual booksellers' sites. It does include ILAB-LILA, so you could start and end your searching here, but you also get a lot of what I might call "extraneous" listings. The thing I like about viaLibri (besides the name) is that you can see a huge range of sellers' prices for most titles, and you get to know who values books high and who sets prices lower. This information will help you interpret the information you're seeing--and will also come in real handy when you go to buy something later. (And, if you get frustrated with the huge numbers of hits for popular titles, you can uncheck certain databases in the upper right corner of the main search page.)
Your Old Books
Really the best place to start, if you are new to the used and rare book market, is Your Old Books, a publication of the Rare Books and Manuscripts Section of the American Library Association. Plus, there's a little section on donating your books to a library (in case you decide they're not worth selling for cash!)
ABC for Book Collectors (PDF)
For amateurs who don't have a sense of how to read booksellers' blurbs and want to know more of the lingo, John Carter's must-have reference is available online from our friends at ILAB-LILA.