When your soundtrack isn’t even completed much less released (not until November 4th), yet it’s already in the Top 5 Best-Selling Albums on Amazon based on pre-sales alone, you know you have a hit. When Borders makes an exclusive calendar and sells out the first printing in a matter of days, you know you have a hit. And when the new trailer to your movie surpasses 3.5 million views less than 48 hours after its online debut, you know you have a hit. Which is why Summit Entertainment’s CEO Rob Friedman is already readying a Twilight sequel — even though the vampire tween/tween movie isn’t set for release until November 21st which is the date vacated by Harry Potter And The Half-Blood Prince. Oh, and did I mention that Twilight has the fastest selling licensed merchandise since — you guessed it — Harry Potter?

But the comparison with Harry Potter ends at cost: Twilight came in at only a $37 million negative cost. This notion of a low-cost blockbuster for a start-up studio just doesn’t happen often in the film biz. So if the movie lives up to the advance hype, Summit will be sitting on a big new franchise. How big? Well, the new Twilight trailer played with Quarantine this weekend and as soon as the title came up, a chorus of high-pitched screams of joy emanated from the women in the audience in one Southern California theater. Only to be properly drowned out by a loud chorus of male boos. It’s conventional wisdom that boys won’t go because there’s not enough gory fang action. But Summit is also marketing to an online contingent called Twilight Moms because of the chaste love story set in the picturesque locale of Oregon and directed by thirteen‘s Catherine Hardwicke. Still, I think Summit is lowballing by hoping for a $20M North American opening weekend from 3,500+ venues.

Like Potter, Twilight has a built-in audience of book fans with, a total 7.5 million domestic sales for all four Stephanie Meyer novels in the series which was a New York Times #1 bestseller for 59 weeks. Not to mention big sales overseas like Italy, Germany and the UK. That’s one reason Twilight is opening day and date in 10 territories, including the U.S.

Summit may spend in the high $30sM for P&A. That’s a bargain consider skyrocketing marketing costs in the movie biz. That’s because indies these days must spend more efficiently than studios by not just attracting long lines at Comic-Con but almost solely relying on My Space and other social networks instead of costly TV ads. Look, for example, at how Summit rolled out the new trailer. First, Nancy Kirkpatrick (one of the best in the biz) heightened fan anticipation by creating a countdown clock to the widget. Then came the trailer’s free debut on Entertainment Tonight. That night, Summit gave fans a special opportunity to see it online first as a way of thanking them for their support. The trailer was streamed through Twilight’s widget from 8 PM to 9 PM for fans, then debuted for the general audience in HD on MySpace Trailer Park at 9 PM. The result: 2 million views in the first 24 hours on MySpace alone and 3.5 million views in cyberspace within the first 48 hours.