The web design industry has huge variability in terms of skill and pay levels. This is largely due to the relative ease of designing websites. High school kids can design a website. So it really depends on the market you want to reach, and the expertise you want to offer.
Do you want to design $100 websites for small mom and pop start-ups selling hand-made bird houses or flower arrangements? Or do you you want to design sites for mid-level companies? Or do you want to move your web design business more in the direction of brand design, brand management, and online marketing for larger companies?
Our company works with regional-sized organizations: Wine Boards, Departments of Transportation, Art Museums, State Universities, and we've done work with MSN and Microsoft. At these caliber of organizations, they look to us for branding, marketing, Interactive, and database application integration. These are serious projects which require people experienced in high-caliber graphic design and branding, software engineering, and marketing. Projects range anywhere from $10K - $500K and more. Depending on your skill level, you could earn anywhere from $50K-$110K / year as an employee in a good web design company.