The Nismo is the way to go, i got mine brand new off the showroom floor for $33,000, you can get a good deal on one if you shop around. I looked at a few of the new Z's, but there was no way i was gonna buy one unless it was a Nismo, it stands apart, the new 370 is rare as is, add the limited Nismo package, and it gets even better.
Upgreaded wheels (my favorite), suspension, interior, body kit, 9hp from com, 9hp from exhaust...just my own opinion, but i wouldnt have a Z if it werent for me running across my Nismo...
Oh, and ive had at least 5 people legit think that it was a porche...Ladies love the Nismo