Mine was new -- I bought in April '03 and saw another one show up at work in August. Turns out msfiveiron lives near the dealership that car came from, and remembered looking at it on the lot -- but it wasn't from a Nissan dealer! So I saw my first used one nearly a year ago.
I'm more interested in finding them totalled in junkyards for parts. Now that I cut the wires to my screen, I'd like to get a new wire bundle that goes from the display controller to the display so that I may fabricate a Y-adapter to tap the RGB, sync, and ground lines more cleanly.
When I bought mine new I had originally intended to buy used. The closest used one I could find was about a two hour ride. Seems to me that the list prices on the used were/are very inflated anyway. I was able to get a new one for much less than what I saw the used being listed for. Of course that was without bargaining on the used ones so I don't know what the final outcome would have been. ZI used Autotrader and found quite a few but none close enough to warrant the hassle ( I had a trade in).
Like EasternPA said, I saw one on a megadealer lot early last summer. I was a blue SL - don't remember the price on it though. I also remember them having a VW Beetle right when they first came out (VW is not one of their ranchises) and selling it as a pre-owned for probably a healthy markup.
Ironically enough, this megadealer is almost direcly across the highway from a Nissan Dealer that obviously had them on the lot new.
Prior to buying my new MO SE, I saw one used 2003 SL AWD listed at $30,000. I guess that they're still relatively new, so the used MO prices aren't going to be much lower than a new one purchased close to the dealer's invoice price.