Amazon's prices definitely ramp up and down.

Put some items on a wish list and observe the price fluctuations over a year or so. Pretty dramatic pricing changes.

DVD movies that were $ 4-5 dollars before Christmas are now $8 or 9 dollars.

Things on a wish list that had declined 20% or more since being added to the list are now not showing as being discounted and are back at the price when added to the list.

Seems if you add an item to a list and track it you can often find it at a discounted price later on. Have to be patient though.