Excellent source for used, rare, out-of-print book prices, AbeBooks is a network of over 13,500 independent booksellers.
Antique Book Values
This web page provides information about books and leads to a variety of resources to use for locating the value of a rare or antique book. For a brief explanation of what makes a book valuable versus just old, click here.
Links to online information about all areas of the antiques world.
Collectors.Org Flea Market Directory
This directory provides information on some of the major flea markets, listed by city under state headings. There is a wide range of events included, from traditional "flea markets" to farmers markets, antique markets, court days and traders' marts.
Check this site for antiques, collectibles and just about anything else you're interested in buying or selling.
Kovels Price Guide Online
Learn from the experts what is real, what is fake, what is a reasonable price.