You might find this interesting - I remember that Heath was looking for something along these lines. If you leave the field blank, it will bring back every grayscale image in the Prints-For-Sale directory - though I'm still trying to figure out how to get it not to pick up the index files though. But generally if the text you are looking for is in the page, it's picked up.
Here's the search page using google image search. It's still pulling up the index pages (which I don't want), but this is about the most useful thing I've found for searching particular parts of the site and returning images. It only returns jpgs that are "grayscale." There are some other parameters I can fool around with as well.
