I did it to my silver 91 several years ago and I am really happy with it. Wish I could remember the cost. Since there are hard edges (seams, etc) it is easier to match colors (no blending). I would expect it to cost anywhere from $500 to $1500.
Get a couple of estimates from good shops - it doesn't cost anything to get an exact answer to your question except a little bit of your time.
The job on my 92 Formula White NSX cost around $750 by one of the best shops in town (Eastside Seattle, WA). There was other work done to the car, which may have made the price reasonable. You can see pictures by going to the site below, and clicking 'project NSX'.