But even at $100m/launch, a big fat copper wire (IIRC aluminium is better per unit mass) would still make more sense than shipping up a nuclear reactor or a huge pile of batteries, and that part of this hypothetical mission would still be about 80% cheaper than the JWST.
I wonder, how hard is it to make aluminium from the oxide if you're bootstrapping and in a vacuum? I know the normal process is "melt it with added cryolites and apply current for electrolysis", but if the goal is low mass rather than good energy efficiency, can you do it a different way? Like, what happens if you focus sunlight and just melt it, does the oxygen bubble out in a vacuum, or is this just going to do vapor deposition of sapphire on all nearby surfaces?
That would bump that number up to ~$10m/$20m or so. Still ridiculously cheap and not likely to be anywhere close to the price charged as it would absolutely sink the rest of the market, which SpaceX is not interested in doing.
Starship is supposed to be cheaper, the moon is definitely more expensive.