I think your one page website is excellent - perfect for selling the e-book. Simplicity is best every time.
In fact I clicked on the buy button and was sent to what looked like Mark's actual page - and it's not a patch on yours!
One suggestion. Your one page website targets web designers who like to design but don't manage the business side of things well. If it was me I would create a similar one page website to target people thinking about becoming web designers. It just might be that they are the ones looking for the information in Mark's book.