Where To Find New SEO Clients?

In episode 107 of the weekly Hump Day Hangouts by Semantic Mastery, one viewer asked about the best places to find new SEO clients.

The exact question was:

Hi Semantic Mastery Team, I have a question about client acquisition. Currently I am using craigslist and spam email to generate leads. Unfortunately for me, I am getting clients that can only afford $500 month or less fees. Obviously I am fishing in a bad pond. Where else can I go fishing for new clients?