How do you make money as a developer? From selling or building websites?
I started off selling Drupal websites for $500. It took months longer than I thought to deliver the projects and I didn't make any money. I gave up on freelancing and took a job developing a site for a research project.
The price of a product is what a customer is willing to pay. The price of your work depends on who you sell it to. If you learn to make enterprise software, the market pays a high price. If you want to build WordPress sites with off the shelf themes, your range will be limited.
How do you build a practice that earns a great income? The easiest is to apply for a job that pays well. You must have the qualifications and credentials, and it really helps to know someone on the inside.
If you're confident with your skills and opportunities, you can freelance and choose when to raise your rates. If you work 1500 hours in a year and raise your rates $10/hr, that's an additional $15,000 in your pocket. Trust me, that's much easier than working longer hours.
There is a price that's too much, it's when the client doesn't have the budget. It's fine to scope a project to fit a budget, but when the money runs out before things are done, they really crash and burn.
Bigger projects need bigger budgets as assurances that they will go as planned. Bigger agencies command a bigger premium, but bear the strains of managing a complex relationship. Higher price projects are not getting more labor from designers and developers, but a guarantee of continuity as workers burn out or move on.
To profit in this industry, value your work highly and market yourself well. Keep your opportunities open by meeting new people and sharing your interests. Work your way into a role that makes you happy.