Getting 'themed' images for a web site

Building a small site as a simple web presence, want to have a look where the images have a 'theme' of sorts, so it looks cohesive. They might be graphic images, not necessarily pictures. I want something that doesn't look 'generic', and I don't want to use stock photos. For those of you who have done this for your sites and products, do you just go to one of the freelancer sites and find a person? Any tips? Thanks in advance.