Skyscanner - Skyscanner.com compares over 1000 airlines to find you the cheapest airfares, fast.
AliPrice - AliExpress Price Tracker app lets you track the price history of any item from many online retailers like AliExpress, Daraz, and Amazon, etc.
KAYAK - KAYAK is a travel search engine that searches hundreds of other travel sites at once. Our helpful tools & features find you the information you need to make the right decisions on flights, hotels, rental cars and vacation packages.
idealo - Idealo is a free to use mobile application that helps you to find products, compare price and make an informed decision.
DealExtreme - Online shopping for cool gadgets at the right price.
Camelcamelcamel - Easily monitor Amazon product prices and get alerts when they drop.