I was listening to Amazon sellers on TV a month or so ago and they said they can update prices as often as they want -- every minute or so if needed. I have noticed that if I look at something on Amazon and go to the Walmart site or some other site and look at the same thing then go back to Amazon a while latter the price has dropped. I have also noticed that if I leave items in the cart as save for later, the price rarely goes down but will inch up -- sometimes by pennies.