Different cams, ecu, pulleys, not to mention none of the pedal/clutch stuff in place. Yah.... pricey!
I don't think anyone keeps rebuilt NSX cores in stock b/c of the exclusivity, so plan on some downtime.
Also, the whole "auto's don't sell" argument is kinda null, given they are really rare, and there ARE buyers looking for them. The one I bought had three buyers lined up if I backed out. Just look in the top forum to see people lookin now!