"The resale prices you are seeing are not surprising since for not too much more one can buy a brand new, current low-end camera with improved features. For instance, on B&H right now you can get a brand new D3100 with 18-50mm VR lens for less than $500. Given that, how much should a used D200 be worth?"
Yes but... Some of the new entry level cameras cannot auto focus all lenses and recently I learned that some also do not have flash Master command mode to control other flashes. There may be more but just those two points will cause me to hang on to my older DSLRs.
Regards, Clive Liddell Pietermaritzburg South Africa