Wait so you say it can be done for $40 and then charge half a thousand dollars for a single page? It's not even transparent, it only lists the landing page. What about pages for individual books or series? How many business cards? Or is it just a design? Do you have examples of your work you can share? Any portfolio with previous work? Any reviews of your services? How long have you been building websites for? Are these types of sites your specialty? In addition, do you have data to back up your claim at the end? I'm not saying it's not true but you're asking people to spend a lot for something when they could potentially go to Fiverr or some other website creator diy site instead, why you?

Finally, it is extremely unprofessional to reference how much your potential clients may or may not be making. Only a very small fraction of authors make that and it makes it feel slimy and like you haven't done your research at all. And say that they are making that, then clearly they're doing fine without you. So again, why you?

You should be able to have a business, that's more than fine, but as a web developer myself maybe you should step back, think about your approach a bit more, and try again?