[NB: This was posted in 2007, when I was selling books at halfredhouse.biz . Unfortunately, I am currently unable to sell books at this location, and must ask you to disregard references to books for sale.]
While I would love to have you buy books from me directly or via Biblio.com , I think it’s only fair to point you to some resources for finding cheap books that are actually cheap and are likely to really be available.
The first thing to do is price-comparison, and the best place to do that is at Fetchbook.info. They list books by Title, Auther and ISBN and provide a list of online booksellers that have a copy for sale, ordered by price. They have a neat feature that gives you the total price of the book with shipping to your location.
Nevertheless, if you find the book you want listed for a penny or thirty-nine cents, there are some other things to consider before ordering it.
Remember that even if there is an online bookstore listing the book you want for one cent, there is always a shipping fee. In the US, if you buy one book and have it shipped by media mail, a fair price for shipping is $3.00. Overseas shipping is almost always by airmail only, and from the US it may average $9.00 . Some dealers, including certain very large operations, count on their shipping fees to make a decent profit on books they price at a penny; if the dealer asks for $6.00 per book for ground shipping, buying from that dealer is probably a bad deal. Buying from a dealer who is not only in the same country but in the same region of the country is usually a good deal, since ground shipping will be faster.
Often dealers with lots of penny books are also highly unreliable in other ways. Some list books they don’t actually have in stock but expect to order from another source and drop-ship if someone orders one; this can mean delays of weeks or months and frequent cancelled orders.
Bookseller ratings may or may not be helpful; I don’t trust them much. Dealers who list on eBay or Amazon.com receive ratings based on customer feedback; these ratings are subjective, so you need to look not only at the quality rating, but also at the number of customers who have provided feedback.
Fetchbooks rates agencies, not individual dealers, based on their “fulfillment rate”, the number of orders successfully filled. These ratings are not very useful for sites like Biblio.com, which list a large number of dealers whose performance varies widely.
Sites like AbeBooks.com, Biblio.com and Alibris.com rate booksellers based on the number of orders fulfilled. Again, you need to look at the volume of orders as well as the raw rating: My rating at Biblio looks pretty poor this month, but I have filled most of the orders I have received very promptly and satisfactorily. The poor rating reflects the fact that during a power outage, I lost some information from my database and ended up continuing to list several books I had already sold. Because I had a very low volume of sales, unfulfilled orders for two of these books dragged my rating way down.
When ordering books, I find it more reliable to look at the bookseller’s online store for evidence that it is run by a human being or that it is tied to a “brick-and-mortar” store that has a good reputation. Again this is subjective, but if you’re like me you probably trust your own subjectivity more than someone else’s and more than mechanically-generated ratiings. Trust your intuition or the Force, or whatever…
If cheapness is not your only criterion in chosing a copy of a book, you may want to look for expertise. I’m happy to give advice about what I know, but for book-collecting expertise, I recommend going to the Antiquarian Booksellers’ Association of America (ABAA) or one of its international affiliates. Look up an ABAA bookseller who specializes in the kind of book you are looking for and ask for advice. The members of this organization have been in the used book business longer than I have and are generally very helpful. Prices at their bookstores are likely to be higher, and things like edition numbers and peculiar bindings matter to them in ways that they don’t matter to most cheap-book-buyers (most of us, I suspect).
Please feel free to ask me about anything remotely related to this book business. If I don’t know the answer, I’ll tell you, but I may have run across exactly the information you’re looking for. I am a human being and generally well-liked by people I see regularly 