No surprise - S2000's have held their value very very well. For one thing, they're pretty rare, for another, they're great, and most importantly, they're a Honda, from the tail end of the glory days, when Honda was just giving away massive amounts of value. Honda was making $50k cars and selling them for $25k.
(aside : there's some sort of vague sense in which I believe Honda from somethinge like the mid-80's to the mid 90's made the greatest cars of all time; obviously not in terms of actually comparing them to modern cars, so that forces me to qualify it as "compared to their era" and then you get some moron who says the dupendinger hummdorf from 1910 was a bigger improvement over its era, which, okay, I have no fucking idea if that's true or not, and I don't care (and I doubt it), so I hate all that "good for its time" kind of rating. But anyway, when you look at the line from the CRX, the NSX, all the Type-R cars, just staggeringly good, so well made, reliability, perfectly tuned to give the driver the feedback and control he needs, and way way underpriced, so much more car for the money than the competition; it's a damn shame that that time is passed)
On the other hand, RX8 prices are falling fast, and something like a 2007 RX8 for $15k is looking pretty attractive -
Sometimes I go off on these flights of fancy about getting a 240Z or an E30 M3 or some cool old car like that, for the wonderful analog-ness of it, the lack of driver aids, light weight, direct steering. But when you can get an RX8 for the same price, come on, it's just better, much better. And then you don't have to deal with it being in the shop all the time. I like cars and all, but my tolerance for dealing with mechanics is very close to zero.