According to Google, they have a traffic value of over 220,000 visitors per month which is roughly 50,000 visitors per week. Since they have sold 500 copies in two weeks, or 250 in one week, they are converting only 0.5% of their traffic. While that is a very small number of sales to visits, we can see just how important internet traffic is.

That said, $15 for a quality e-book seems a fair value. Check out the sample pages here: http://www.underconsideration.com/flaunt/