You can create your own ebook store in wordpress easily. In this video, I have shown how to do that. I have used a plug in called 'ebook store' to do this.
I have shown how to install the plugin and how to configure it. I also showed how visitors of your website can buy ebooks from your store. I have used paypal sandbox to do that for testing purposes to show how it works but you can change it to your original id once you are done with testing.
I also showed how to create categories and categorize your ebooks in your store.
For more details watch the video.