Lotus offers some really nice track cars for relatively cheap (unless you start looking at Exige). These are precise, light, fast, and mid (or rear) engined... I'd get that given the costs of tracking an NSX.
You may want to check with the track event organizers in your area before getting an S2000 (or any other convertible) with the intention of tracking it. Some track events allow convertibles without restrictions, others require a full roll cage, and still others don't allow convertibles under any circumstances.Has he considered an S2000?
I'm going to add a little love for the S2000, especially since your friend is a Honda devote. With his budget he could pick up a nice S2000CR. A couple not far from here takes their CRs (they each have one) to autocrosses all over this region and absolutely dominates their class, often also taking best time of the day honors to boot.
If that weekend driving needs to be top-down but with a soft-top just in case, a regular AP2 S2000 could be just the ticket. And the extra cash would allow your friend to put in a very high end suspension.
Dave. When I first joined prime you told me to wear Capri pants and drive my car.
**Edit:
you told me not to wear capri pants and drive my car
nevermind