SEO for Dummies: Is a Picture Worth 1000 Words?
No. In terms of content, a picture is generally not worth 1000 words.
I have experienced the occasional blip in traffic when a photo on a blog ranked on the first page of a Google Image search for a popular term, but this is rare and I think that it is hard to make it happen deliberately. One thing that you should keep in mind is naming your image files using relevant keywords.
As far as copyright law goes, you can find lots of free photos on the net, or you can take your own pictures. I would only consider buying an image if I was planning to make it an integral part of a page layout.
