idealo - Idealo is a free to use mobile application that helps you to find products, compare price and make an informed decision.
Price Tracker for Amazon - Price Tracker for Amazon is a shopping app that allows you to browse for favorite products from famous online stores know as Amazon for a better price.
TargetBay - TargetBay is a complete eCommerce revenue generation platform.
Google Shopping - Find the best products, prices and places to buy
Camelcamelcamel - Easily monitor Amazon product prices and get alerts when they drop.
Keepa - Price history charts and the option to be alerted on price drops for all Amazon sites.