Possibly useful in the future: are you aware of the thousands of photos online with a Creative Commons or free re-use license?
Google Images has a Tools > Usage Rights filter where you can select from a variety of free re-use license types.
Flickr.com, under “Advanced” search, has a license drop-down (it reads “Any License,” but when you click on it, you’ll see a range of usage rights.)
PaintMyPhoto maintains a huge source of free-use photos at pmp-art.com.
Creative Commons has a fairly universal requirement that you acknowledge or reference your source, but that shouldn’t be a huge stopper. I don’t remember any restriction whatsoever at PMP.