How well a book sells is heavily dependent on what the author's goals are and how actively they choose to promote their book. Some authors are very visible, talking on the radio, organizing book signings, and reaching and exceeding their sales goals . Higher-selling authors have sold over 5000 copies so far. On the flip side, some authors that have only sold a few copies, mostly to friends and family, because that's all they wanted to sell. I believe that authors will sell more and more copies as we continue to patronize services that will give them the ability to market their books more effectively, but in the long run, sales are a reflection of each author's goals. If becoming a bestselling author is your goal, you will be working to achieve maximum sales. If you are publishing your family's history or a personal memoir you may only wish to have your book available to family and friends. How well your book sells is entirely up to you.
Try this book trailer perhaps?
http://bit.ly/kfzAa