You don't have to wear out the engine to do an EV conversion; you just sell it to someone who needs a good one. In my case I have a host car in perfect condition with a refreshed suspension, and I own it free and clear.
That does put you a step ahead. Most people would have to buy the rolling chassis or host car, and the better its condition the greater the cost. A Miata in good condition would set a person back a good bit.
Disagree, though of course I recognize that one gets what one pays for. But the new roadster is clearly designed to compete with exotics like Ferrari, Lamborghini, McLaren, Audi R8, Porsche 911 Turbo, etc. that are beyond the means of all but a very tiny minority. Where does that leave the rest of us that just want an affordable fun commuter/weekend car?
Old Tesla Roadster, used. You'll get a much better car for less than you could make a similar one.
but:
I think that successful businesses organized around doing a truly professional job of converting ICE vehicles to BEV seem plausible. I gather this takes about 200 hours of labor (a long work month) per vehicle on a custom basis, which should drop with some specialization to particular vehicle types. With battery prices dropping, and BMS getting more refined all the time, the total cost would be less than Model 3 pricing. Certainly if one wanted a sport sedan, it could make more sense to buy a Model 3 than to convert a BMW 3 series, but if you want a BMW coupe, or an Estate wagon, or a convertible, or a crossover SUV, it could well make sense to go with a conversion. It may be a long time before Tesla can compete with BMW or US makers on model diversity.
I'll grant you this: If you want a BEV with a 40-mile range that does zero to sixty mph in 15 or 20 seconds, and you happen to own a suitable donor car, and
if you find a truly reliable conversion shop (and I learned to my great cost that not all such shops are reliable*)
or you can do the work yourself, you can probably do it for less than the cost of a 245-mile, 0-60 in 4 seconds Old Roadster.
* Buyer beware: There are shops out there that appear reliable and put up a really good front, but that are not competent and will return your car to you essentially ruined.
As for there being a profitable market niche for a reliable, competent shop, employing competent mechanics and paying them mechanics wages and using quality parts, I believe the market is just not there. Even with the limited availability of models (Used Roadster, new or used Model S, Model X, Model 3, Bolt, Volt, and a few low-volume offerings from other companies) the vast majority of potential EV buyers will find one of these more desirable than a conversion of uncertain quality and questionable reliability. A conversion car will always be a project car: If you love tinkering with cars, this could be a fun and enjoyable hobby. But if what you want is a car you can drive whenever you want, even a car from GM will be more reliable.
The New Roadster is a hypercar for the uber-rich to give Tesla bragging rights. Conversion cars are for hobbyists.