I agree with everything you said.
Maybe, a horror movie would work since those tend to have budgets less than $10M.
Actually, I would love to see them market something like 50 shades this way. Also, for what it is worth TPM did not have any US TV spots. There was a lot of advertising, but that came from Pepsi and Pizza Hut and whatnot promoting the film with their tie-in promotions, and that was before social media!!!!!!! I think I recall reading somewhere that George Lucas spent an entire $10M marketing the film, and I think that was for trailer prints and OS advertising.
Also, look at how big THG opened. I believe it had a pretty small advertising budget (compared to other movies that opened to $150M).