SEO is the most viable route for most if you are willing to learn and work hard. Word of advice, don’t build one site and expect it to make you rich, Google won’t list you very high until the site and/or links mature over time so you will need to rely on Yahoo etc. at first. My experience with Yahoo is that they don’t always pick up everysite you build, I count on 1 out of 4 doing well, the rest seem to get looked over for no apparant reason.
Just my 2 cents…