I'm torn between the NB/NC models. Coming home in a few days so will try and drive both.
The 135 I drove got sold, apparently to a dealer, then I called the dealer...and he sold it as well. FML.
You might be better off getting a later year NA Miata (with the 1.8L) over the NB if you are going to spend the money for a clean one. Clean NA's are entering collector car territory whereas NB's haven't seen the same appreciation. You lose 10hp but its also over 200lbs lighter. I've spent a lot of time in both and they drive very similar.
NC is much more daily driver / tall person friendly. The hardtop option cuts down on driving noise substantially.