A few months ago Google announced they would be getting rid of Google Product Search and be changing it to Google Shopping, so instead of delivering product results, prices, and reviews from all around the web, they are simply allowing users to search for products from merchants who pay them advertising fees. They sent this to merchants:
We're writing to let you know about some upcoming changes to the product listings you submit to Google. As we recently announced, we are starting to transition our shopping experience to a commercial model that builds on Product Listing Ads. This new shopping experience is called Google Shopping. As part of this transition, we'll begin to enforce a set of new policies for Google Shopping in the coming weeks.
...blah blah blah...
What product search and price comparison tools are available as a replacement? Almost no products exist in Google Shopping anymore - it is hard to use it to find a lot of specialty things.