I hate to sabotage anybody else's sale, but I think I let my stock Nismo exhaust go for $225. Maybe I got ripped off... but as everybody is saying, much more and you could go aftermarket.
The carbon fiber FI exhaust sounds AWESOME. I've had people that don't even own Zs approach me and ask all kinds of questions and multiple females have described the sound as "sexy", which is a win as far as I'm concerned.
The nice thing about the Nismo CBE is that there's not much (if any) drone in the cabin. Even with the 12" resonator on my FI CBE setup, it's hard to talk on the phone and I can't really listen to audiobooks at a reasonable sound level, even on an aftermarket stereo setup. Music is fine.
Hope this helps.