Ask HN: Is my startup idea retarded?

Jason Calacanis recently tweeted that he is looking to fund an open source alternative to facebook which reminded me of this idea I once had for a "Phone Book of the Internet." There's a website that already does this, whitepages.com, but they're sort of a scam as they require users to purchase a subscription in order to look up one phone number. So what do you guys think, is a Phone Book of the Internet a stupid idea? I think it's a really great idea, the only problem I've run into thus far is cost. At around $1 a pop to acquire each name:phoneNumber pair, it would cost around $100,000,000+ to gather the majority of adult cell phone numbers here in the United States. Any thoughts? comments? Feedback would be appreciated. Thanks!