) best selling product of all time, beating out the third book in the Harry Potter series. Amazon has said it's sold over 8 million Kindles, far more than anyone expected. In the press release noting this achievement, Amazon said, "Customers report using their LCD tablets for games, movies, and web browsing and their Kindles for reading sessions. They report preferring Kindle for reading because it weighs less, eliminates battery anxiety with its month-long battery life, and has the advanced paper-like Pearl e-ink display that reduces eye-strain, doesn't interfere with sleep patterns at bedtime, and works outside in direct sunlight, an important consideration especially for vacation reading. Kindle's $139 price point is a key factor — it's low enough that people don't have to choose." Shares of Amazon are down 29 cents in pre-market trading to $182.30.