I'm no expert but that price for the tour does seem high. My co-worker and I have a private guide & driver (one day - guide drove us himself on day 2) for $400 ($100 each per day for 2 days; well, day and a half and he drove us to the airport after the Wall at Huanghuachung on Day 2) which is about half what you were quoted. You are getting more, but I'm not able to discern if it's twice as much more ;-)
http://www.flyertalk.com/forum/china...l#post25881888