SEO is a great profit centre for a lot of companies because the term itself 'Search Engine Optimization' freaks a lot of people out, especially ones that aren't too familiar with search engines and how they work, that makes the service worth more already.
From my own personal experience and from what I've read etc. You can save yourself a lot of money by doing it yourself (haha and make more by charging others for it) and the search engines really don't care how much you did or didn't pay anyone!)
