Hopefully these links will help provide you with useful information about purchasing images, either for some queries on pricing or for a look at some great stock photo sites.
Stock Photo Price Calculator: this site is an online guide to some stock photo prices. As always, it's a guide rather than a definitive, but it should help you get some idea of what what the potential cost for pricing an image might be.
FotoQuote: A great investment for anyone needing to regularly research stock photo prices.
Stock Artist Alliance: A website and organization offering a great deal of support for stock artists.
The Stock Asylum: A wealth of information about sotck artists and stock photos.
About Arts: Directory of photography related websites and discussion groups.
Guy Tal: The work of photographer guy Tal. Extraordinary images, largely of the desert southwest.
Michael Gordon Photography: Michael's work is sublime. For Fine Art Prints of the American West, it doesn't get much better than than Michael.
Ron Niebrugge: Ron's work is great, and he's a super nice guy too. For stock photos from Alaska, the Canadian Rockies, and much of the West Coast, check out Ron's site.
Mark Graf: Mark is an awesome photographer, with some really cool images. He's based in SE Michigan, but don't hold that against him. Definitely take a look at Mark's site for some great and diverse photography. His blog on that same site is pretty cool too.
Gary Crabbe: Gary specializzes in spectacular scenic images of the United States, National Parks, travel destinations, outdoor recreation, and other subjects. Super great photographer.
Philippe Wiget: Philippe is a Zurich based photograher with an outstanding collection of travel, people and location photography. He also specialized in shooting events and corporate photography.