Prices for books move around more than I would have thought. I can understand the Amazon price drop on Stephen King as mention in the article because it was an

Prices for books move around more than I would have thought. I can understand the Amazon price drop on Stephen King as mention in the article because it was an analyzed move to compete with Wallmart. (price history graph: http://www.shopobot.com/under-the-dome-a-novel-hardcover http://www.shopobot.com/under-the-dome-a-novel-hardcover) But why do some book prices swing wildly up and down day to day? ex. http://www.shopobot.com/where-the-wild-things-are-hardcover http://www.shopobot.com/where-the-wild-things-are-hardcover Do they dynamically price based on sales that day? Anyone know how Amazon's pricing system works?