[Jeph]

If it were me, and I was deciding between those 3, I'd go for the NSX. It's a sweet sounding car... It's a Honda. It turns heads more than the other two ever could. It's got healthy performance numbers. Getting an '02, as some one suggested earlier, is probably out of your price range judging by the fact you're looking at used E46s.

Now then, if TOPLESS didn't have to be a requirement, I'd say M3 (maybe with a sunroof?) hands down. In fact, why won't a sunroof cut it? The M3 is a serious machine, but a bit on the conservative side (in terms of looks), but a contender nonetheless.