Editors' Note: The Download Now link will prompt a local download of the Firefox extension. To install the extension directly, open the file using your Firefox browser.
InvisibleHand is an extension for Mozilla Firefox. Automatically get the lowest price when you shop online or search for flights. InvisibleHand shows a discreet notification when a better price is available on a product or flight you're shopping for. Covers over 220 retailers in the US, UK, and Germany.