Actually, the last time I went into a Dodge dealership (to look at a PT Cruiser, of all things), they had an ACR Viper and a standard Viper, both selling for below MSRP, the ACR around $15,000 below. It actually got me thinking, until I realized what I was contemplating and took the PT for a test drive.
But a Viper might well be had for less than an NSX, new vs. new - depends, as always, on how willing both dealers are to part with the cars.
One thing I've noticed with sports car comparisons and discussions with folks at work, folks that are at least "somewhat" interested/knowledgable about cars, is that the NSX is seen as a joke. A friend at work drives a 2002 WRX, another a Honda Del Sol - most other coworkers consider my NSX to be in the middle in terms of performance, and that's a hard stereotype to break. I actually had to *show* the person with the Del Sol that my car was in fact faster, but he still insists that his car handles far better than mine.
When someone sees a Z06 on the road (and, even in a relatively sportscar-free area like Austin, you will pass 1-2 every day), they know it's a fast car. I think that's why it's getting compared to so many cars - right now, IMO, it is the performance leader for cars to the Generic American (tm). It's getting compared to Ferrari, Porsche, the new Mustang Cobra, older Camaros, everything that people generally associate with performance. People that see riced Civics think of it when they laugh.
To me, if Honda wants to regain the performance car title, like how they took it (or at least validly challenged it) when the NSX was released, then they *need* to beat the Z06 - right now it seems to be the PR king of the hill...
Now, to be honest, I think a little more torque on the NSX would be nice, but if they had to add enough performance to beat the Z06, engineer lightness, etc., I don't know if I would even want the new NSX. It might lose what it means to me, mainly, a solid balance of what a car should be. To each their own, but I'll be sticking with my '92 until something better comes along - IMO nothing has, yet.