How do early stage startups recruit hackers?

I am considering providing hacker recruiting services specifically for startups (bootstrapped or in seed stage), but I am not sure if I should establish my channel strategy directly to startup founders, or through recruiting agencies/headhunters. So, my question is ... how do early stage startups recruit hackers? Do they only rely on people they know? Do they hire headhunters or recruiting agencies? Do investors have a say on how/where you should hire the dev team?