You would need to be very specialized in SEO in order to grab a good profit Once you get your name out there, you can start charging few hundred dollars per hour like Aaron Wall.
I would broaden your studies to 'Internet Marketing' to maximize your value in the market. SEO simply isn't a sustainable career IMO. Most of the folks I know really do far more than SEO such as SEO Social Media Marketing PPC strategy Paid Placement (online advertising) Promotion ( getting noticed, link baiting ) Analytics and conversions Geo-targeting ... and more... I am unsure, going forward, if simply having some SEO knowledge will really cut it for staffers in the SEO arena... I started a web design company 10 years ago and now have that as well as a marketing company, SEO company and even a hosting company for a bonus... Point is that diversity is big and my talents from one transposed to the others. My background in web development helped a ton when we got into SEO.... bla bla bla.... SO I say study the broader 'Internet Marketing' world... wihch ultimately includes SEO....