If you're considering a much more in-depth ebook, why just make it ebook? You might actually consider getting it published (you can self-publish it with a variety of services available) or you could find a literary agent and attempt to get it published by a publisher.
I recently recommended to a friend that he not publish an ebook and, instead actually try to get the book published. It just came out recently, published by McGraw Hill, and I picked up a copy of it at my local Barnes and Noble. So, it's very possible; if you're a good writer and have a great idea for a book, then don't 'sell yourself short' by settling for a self-published ebook.
I'm not saying that publishing the book as an ebook on your website isn't a good idea and that people aren't making a lot of money doing it. But, you may be surprised how easy it really is to find a literary agent and get it published by a publishing company.
SEO since 1996, I've been doing internet marketing. I have the experience as an SEO expert
, as well.