I lived in Glen Park a couple years back (it's a suburb in SF), and was able to land a two bedroom apartment for $1000. That's as cheap as it gets in SF, unless you're really lucky.

Have you tried Craigslist.org? For business related stuff, I've met some nice people through that website. And it's utilize by a lot of communities in the Bay Area.

Do you have any friends already living in SF or in a city nearby? Your best bet is to do what you're doing, going to the social websites and making contacts with people that live in/near SF. Once you meet someone reliable, you could visit for a week and see if SF is really for you.

Personally, I loved it there--there's something happening pretty much 24/7 and there's a ton of small friendly communities you can fall into, if you know where to look.

Good luck man. :)