I have updated AmaCraigBay to include Google Products. If you already installed the browser plugin or bookmarklet, you don't need to do anything to get the update. It should just start showing up. Google products will include a lot more options to compare from, including stores like Walmart, Target, and KMart.
If you don't have it installed yet you can get them from my previous post.
There is a problem when you refine your search. It will currently show the result from your first search after you refine your search. If you want to get the refined results, go back to Amazon's home page, and then search again. You can also click on a product and search from that page. I am working on fixing it, and hopefully that will happen soon.
Thanks to Kynetx and YDN for making this so easy!