I'm involved in the development of InvisibleHand, a Firefox plugin that compares prices of products at online stores in real-time and displays notifications if a bargain is found at another web-site. It's not a startup of mine, I work for the company that develops it.
Right now the number of products in the DB is limited, as well as the number of retailers that we support but we're working on it. You can see the list of supported retailers at (http://getinvisiblehand.com/products-retailers/)
If you install the extension you should get notifications on
- http://www.buy.com/prod/nikon-d40-slr-digital-camera-kit-6-1mp-3008x2000-sd-sdhc-slot-nikon/q/loc/33409/203923451.html
- http://www.radioshack.com/product/index.jsp?productId=2262669
- http://www.amazon.com/gp/product/B000NRG9O6
What do you think of the product? Would you use it? Is it a problem that only one alternative is shown even if more are available? Is a Firefox notification a good idea or a popup window would be better? Is it a problem that occasionally wrong notifications are shown?
Oh, the link: http://www.getinvisiblehand.com/