No rust. No stripping. No restoration. Engineering drawings already done. Just a simple build from plans. Supposedly all the CAD word has been done. This really isn't rocket surgery. Even granting a "complete custom fiberglass" body (as opposed to SMC), and a "completely custom dashboard", and "other interior hard moldings", once they did one set, the second set is cheap. The wiring harness is nothing. Take the Metro harness and you're done. It might need a custom harness with a modern, EFI engine, but we're talking about the existing units. As for "fully outfitting" the interior, again, not brain science. Paul Elio has claimed to have the data on all of the costs of the vehicle. The parts are numbered, and are not countless.
This is not a high-tech, whiz-bang super car. This is a simple, off-the-shelf vehicle that is supposed to be easy to work on by an owner with average mechanical skills. For a realistic assessment of the max reasonable cost to build the 2nd copy of a prototype, take a look at Factory Five Racing's 818. Hand-build chassis. Custom interior & body. Donor car parts. You'll find that my $50k figure is both realistic and extremely generous.
What the forum members might be asking themselves is whether it is reasonable to believe that EMI is capable of selling a fully-spec'd production vehicle for $7300, when they can't build an under-spec'd prototype for testing for under $0.5M. The numbers just don't work. And again, we are discussing the direct costs from the time of turning the first wrench, to driving it out of the shop.
It is very reasonable to build a production vehicle for $7300 when a one-off prototype cost $500K once you understand the reality that it is nearly impossible to make a direct comparison between the costs of building these two vehicles as they are built using completely different processes. Mass production, low volume serial production, one-off custom vehicle building, and one-off engineering prototype vehicle builds are all completely different animals with completely different labor, and even materials costs, involved in the process.