Buying great images for selling templates

I have seen some great templates and they say “images not included in template” Where can I get/buy those kind of images for the templates I am creating?

there are many sites from where you can buy images such as photodune, fotolia.com etc

great tips, how do we go about protecting the sellers? If I buy a HighRes picture, how do I ensure that the client doesn’t download the image from my demo to use it on their site? Is it possible or do we just ignore that issue?