Invoice + whatever taxes and fees are for your state or city.
If something looks like a ridiculous amount ($500 for processing fee, for example), ask to get it lowered or just walk out and go to another dealer.
edit - yes, also wrong section. We have a separate section for pricing questions:
http://www.the370z.com/nissan-370z-p...g-discussions/
And if you can get it for less than invoice, then more power to you and of course that'd be better.