As usual, I failed to take a logical progression of photos during this job, but I did get a few and will include them here. It should give a flavor of what's involved in recovering the Miata seats. I've had slip-on covers on the original seats for several years now but was never happy with how they fit. So, real upholstery was called for. I bought these covers on Amazon for under $150. For that price, even if they don't hold up, I'm not out much. Except for about 8 hours of labor, of course.
One final note - I used a lot of zip ties instead of hog rings. In many cases, it was a lot easier to get a zip tie in place. In some cases the hog ring worked better, though, so be prepared to use both.