Amateur bodies hold value better than pro bodies?

I alwAys tend to upgrade to the latest. Previously I had believed than pro lenses hold their value but that bodies show big depreciation. Four months ago I sold a one year old D3S and a three year old D3X. I was very pleasantly surprised at the prices these archived on eBay.
Regards
Deegee FRPS
http://www.duncangrove.com
http://www.duncangroveblog.com
Q:- What's the difference between artists and photographers?
A:- Two artists can have a conversation without discussing their paintbrushes!