It's funny you mention that site. They actually have an autonomous PTZ that's like $200 here: http://www.thesentryproject.com/Object%20Tracking%20Camera.htm
They are sort of cheating with a price that low because with that system you can get 14M images or 720p video, zoomed in on the subject, all done automatically. It usually costs a hell of a lot more for video/image quality that high and that's not even counting that fact that targets are tracked autonomously. The problem is that they run out of them quite often.
