Check out
http://www.modelperfect.com. It's pretty new, but I'm also buying out another content company and merging our inventory.
I'm currently at $0.20/pic, can do full exclusive for $2.25, and can go as low as $0.10/pic in bulk and $1.10/pic for pre-existing, full-exclusive sets. I should have about 20,000 rarely distributed pictures within a month (the content company who's inventory I'm buying barely sold any of their fully exclusive content).