Quite simply if you can afford the other mods needed to make them nessacry, then 8,000 from Toda will be easily with in your reach.
Some NSX parts are almost impossible to find and sometimes have to be custom fabricated which = $$$$$$$$$$$$. If I get an NSX, I'm going to do EVERYTHING I can before I start getting shit custom fabricated. An ITB will only add like 15hp and increase low-end torque. I don't think $533/1 HP is worth it. I think Mugen makes one but I've had no luck finding it or getting some idea of what it costs. I hardly consider Toda's $8,000 stroker worth it let alone an ITB.