Customers aside, there are tons of people willing to help, either through advice or introductions. There's an entire ecosystem who understand startups, and have been there.
My failed started before that was in Austin, Tx, and the startup density just wasn't there at the time (2009).
Not every developer in SF is as mercenary as you make it sound. For your first employee hire, you might find a single person living in an apartment in SF vs. a family man in St. Louis who has to pay for day care and save for college. Their salary requirements might be comparable. [Edit: my point here is not to say that SF people are only single, and STL people only have kids, but that salaries are a distribution, and that there are places where the SF and STL distributions overlap, based on the individual's experience, desires and stage in their life.]