Not to debate the topic but to give options....

3 layers of 2" urethane foam at R-7/inch get you R-42. No additional stud wall or fiberglass. Where do you run your wires? Perhaps conduit on the outside of the foam within the strapping layer. A baseboard box chase on the inside? Don't forget the interior walls which allow for conventional wiring. If you use a conventional framed floor system you get to use that for plumbing and wiring as well.

I am using 5/4" strapping, 3", 4", and 8"-10" for the corners and window buckets.

One of the worst parts for me is running the pricing numbers, so please excuse me for not going there. Finding a little difference at one store while something else is priced a little higher and so forth.