On Friday I got a Logitech Ultra Vision SE web camera from Amazon.com for  $108.99 – $80 mail in rebate.  Last night I tested it on Ustream and it seemed to work realy well with a good image quality.
If your looking for a good camera with a great image quality I recommend this camera highly if you can find it for a good price.  It is slightly large so it may be better for Desktop use rather than for a notebook or mobile casting setup.
You can find more about the camera here.