I sold all my bolt-on SG copies back in 2010 for about $200-250 each. Can't see them going for much more than that.
Hell, for $599 US I can get a Gibson SG Special!
http://www.musiciansfriend.com/guitars/ ... ric-guitar
When it comes to the LP & SG copies, I think Gibson & Epiphone keep the prices down adequately by offering a new, set-neck guitar in just about every price range (cripes, Epiphone SGs start at $150 US).