As an update:
I stopped to look at the car last week. On the one hand, it seems to be generally very solid. I looked underneath, and though some of the undercoat has been scraped off by contact with something (a speed bump, maybe?), I didn't see any rust or holes under there. There are a few bubbles showing under the windshield on the passenger side.
Overall, the car gives a scruffy impression, especially in comparison to the picture someone referenced at Concorso Italiano a few years back. One side of the front airdam extension has apparently been curbed and needs fixing. All of the wheel arch extensions have been worn by contact with the tires (maybe this is normal with a lowered car having wide wheels/tires?). The engine and transmission are coated with dirty oily stuff, though there are no oil spots under the car.
In short, from a distance it looks great; close up, everything seems to need attention.
Despite its scruffiness, I was thinking of contacting the owner and making an offer for the car, based more on its potential and (possible) history than its current condition. But then something else became available (not an X), so I'm not in the market anymore. For anyone who's interested, I think this car would be an excellent project starting point, but the price should reflect its 2009 condition, not its 2003 condition.
As far as I know, the car has not been back on craigslist since January, so it could be that the owner is not really interested in selling. But here I'm just speculating. Maybe he's just waiting for spring/summer.
Thanks again, wombat, for the inspection writeup, and others for your input.
-Jason
WA, USA