Amazon Price Tracker helps you to list products you want to track on a Google Sheet. It automatically updates the latest availability information and alerts when it reaches a certain price.
PriceAlert for Amazon is a simplified menu bar tool that allows you to monitor the items you would like to buy from Amazon.com and notifies you once it reaches the price you set.
Camel Camel Camel is a price tracker that makes sure you're getting the best deals! You do not even need to make a registration to track your desirable products' prices, you can do that if you want to get alerts. And if you have created a Wishlist in your Amazon account, it watched the price history of all the items that you have not purchased yet.