I'm going to disagree with georgespencer -- not with his perfectly reasonable suggestions, but with the premise that it's not worth seeking out a mentor. On the face of it, nobody "needs" a mentor, but the entire idea behind a mentor is face-to-face networking and advice. In addition, you will be borrowing your mentor's bona fides when you're having lunch with connections you've made via your mentor, and this can go a long way. A friend of mine has Gary Reiner for a mentor -- having that kind of horsepower behind your idea is priceless.

Having said all this, your best bet is to network and seek out introductions. You can't come in "cold", but "lukewarm" is okay, as long as there's a personal connection of some kind to your mentor -- whether it's a shared vision or a shared connection.

ETA: clarity.

I didn't mean to imply that in general it's not worth seeking out a mentor: I meant that for OP it's not worth it because he doesn't have anything he needs mentoring on.

If he needs mentoring on founding his startup or building a working version of his product, he's falling at the very first hurdle (beyond "having an idea"), and also the part of the process which is incredibly well documented online and elsewhere. It's formulaic.

We have two excellent NEDs at my company who are about as good as it gets, mentor-wise. But I'd never have gotten anywhere with them without first doing something.

It's not an uncommon trait in entrepreneurs to want to plan everything down to minute details. Don't be discouraged by that tendency.

If you want to chat sometime, I'm on Gtalk & Jabber 24/7. My email address is in my profile.