After the first full month of business, we have about 50 authors with books that have been in at least a few of the major retailers for about a month now. They are realizing that their books, no matter how great they are, do not sell themselves.
There are millions and millions of books available on the Internet. Your book is just one among the million. It is YOUR job to make sure people find out about it.
I sold about 10 copies of my new book last month. Sure, not "best-seller" status, but I am happy with that number. I am sponsoring a podcast that is related to my book. Each podcast episode, the host mentions my book and tells people where to get it. I don't expect to make my investment back right away, but it is a way to get my book out there. In addition to that I have a custom membership site for my book and there have been a few members that bought my book.
I know it can be disappointing when you check your weekly sales stats and see nothing new. But don't get discouraged -- get frustrated. Use that frustration to motivate you to promote the heck out of your book. There are many ways to do it both for a fee and for free. Just do something.
You have worked hard on writing your book, now put that same energy into marketing it.