It can't possibly cost that much to calculate a trajectory and send a giant single-stage rocket, can it? If we remove the monolith erection requirement, I think this gets much cheaper.
I'd guess that the cost is not just in the rocket itself, but rather the team, research, tests/trials, fuel and logistics of the entire operation. Getting to space is one thing, getting to the moon is an entirely different ball game.
My thought is that we can piggyback on Nasa's earlier work on fuels, and since our goal is just to hit a big gravity well (not at a specific point) our mathematical model for trajectory just has to include the earth and the moon.
