OK, how about hiring hordes of cheap human scrapers from Mechanical Turk? Everything visible can and will be scraped if need arises, the only variable is price.

You're making a distinction that, if you were to actually explain it in a way that makes sense, would reveal a much more relevant solution to this problem.

What's the difference between a machine scraper and a human scraper? Humans use machines to access websites. All your users are machines. And behind every machine is a human.

If you don't want someone to access all your data in a short time-frame, then don't give it all away in a short time-frame.