Goodwin? Flyin' Miata? 949 Racing? Etc, etc. There's plenty...
949 offers nothing for the NC. They did have the 6ULr wheels, but no one bought them and they discontinued. Goodwin has the largest stateside selection of performance parts, but not really anything cosmetic aside from lightweight carbon bits that look exactly like the Factory. Flyin' Miata offers no cosmetic stuff for the NC. Just a rebadged SC system, their sways and spring setup. As far as your etc, etc the only other two I can think of that are doing stuff, performance only, are TDR, Moto-East and Dynotronics here in Texas.
If you want bumpers, spoilers etc you aren't getting it in America. Rspeed will import, but youll pay. Generally speaking, people in the market for $25k cars aren't huge on paying that premium. I can think of one car that I've come across on my years in the forums that has anything from Japan on it. One.
The NC doesn't have a whole lot of aftermarket, Period. So it would be my assumption that the ND will follow the same trend. I could be wrong, but the Miata just has never had the aftermarket support to the like of an S2K or GT86. The NA has quite a bit, the NB slightly less and then there is a fall off with the NC. Even something as simple as FI hasn't been available in a reliable format until maybe 2012, 6 years after the NCs debut. As of this year there are 4, I think, options. You'd think because it's a Mazda there are just millions of options for everything, but not the case. That being said, with good coilovers, beefy sways and a performance tire it's the perfect car. You don't need much.
This is my daily, I bought it with 3 miles on it in 2008. If it's available, I've got it or had it.
Toms Turbine Drive by
JordanColePhotos.com, on Flickr