If you are selling anything, you should have a website. If you are selling ebooks, you should consider it mandatory. How many people do you know who read ebooks but don’t access the Internet? None come to my mind.
The best thing about having a website is that you can quite probably do it free. Later, once you know what you’re doing, you can choose to buy a domain name and pay a hosting service if you want.
You can pay someone to design a gorgeous site for you, loaded with graphics, complete with a secure server and the option to buy right there, but I didn’t. My publisher does the selling. Writing a site yourself, loaded with information and a place to click to send someone to your publisher, is simple.