You pretty much have to buy the NISMO for what it is - most of the extra dollars you are spending is for what you "don't" see.
It is a pretty "bare bones" vehicle; at least from a "luxury" standpoint; especially compared to a decked out Touring coupe or the new roadster...no heated/cooled seats, no nav system, no bluetooth, no leather, etc, etc.
I like the Nismo a lot but I'm likely going to get the new roadster to replace my Touring Coupe...I'll be giving up a little bit of performance but overall I like the open air of a roadster along with all the luxury trimmings.
You will probably have a bit of difficulty finding them for MSRP or less at first; they are, after all, a bit of a limited production. However, once they really start hitting dealer lots I'm sure you'll find a dealer that will make you a decent deal because let's face it, the new car market is in the sewer right now and while everyone is trying to adjust; dealers need to SELL cars.