If you must do an MA: take a look at a place like Miami, OH. Advantage: they have no PhD students there, so you won't have to compete for attention. Plus, they do bill it as a preparatory program. Will still pay crazy money out of pocket, but it seems better than the options you have listed.
Prestige ain't gonna get you in the door. Pick a place that will treat you like a student and not just a tuition check.
Masters programs are at worst a scam, at best (as OP mentioned) a way for rich foreign students who don't mind paying sticker to get to the USA. It's borderline unethical the way top universities trade on their reputation to run these things. I'd stay away if I were you. If you really want PhD, take some math classes at your local public uni and try to get to know profs for letters that way.
Columbia charges 120,000 for their masters in the math department. It's well worth it if you can get into Goldman, Morgan, JPM, Citadel, Millennium, Two Sigma, Cubist, etc.
But I agree with you for PhD admissions. It's better to take math classes at your local university and try to build rapport with the professor.