Furthermore, while your offer won't work, there's also the matter of traffic. If you had the best offer in the world, if no one is coming to your site, or if you're getting crappy traffic, your site will still fail.
If you want a good formula, find a niche which is inadequately served, and serve it with original content available nowhere else.
A "niche" can be a true erotic fetish (e.g., legs, outdoor sex, leather) or it can be a novelty area, like clown sex. Since most erotic fetish areas are way over-served, perhaps a novelty niche would be the best approach.
Whatever you do BUY or MAKE your content, don't pirate it. If you want to make your content, here's a good site (mine):
http://www.girlsdotcom.com/booklets.htm
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Producer of truly original teen/young woman-oriented adult content at
Wonders of the Unseen World