<human>:  Why did the price of a Kindle go up from $99 to $199?
<bot>: The price of a Kindle went up because the price of a paperback went down. When the price of a paperback goes down, the price of a Kindle goes up because people prefer to buy a Kindle instead of a paperback. The price of a Kindle is also influenced by the price of other electronic devices, like smartphones, tablets, and laptops.