Whenever I am buying anything for over a hundred bucks, I start out at ebay. I review the current auctions and then go to the completed auctions and see what the item went for. Then its off to the shopping engines of which Google's service, Froogle, is just one. You can do your straight Google searches for a product, but I find the shopping sites to be more efficient and the information is formatted in such a way that makes it easier to absorb.
However, I can see the day coming where Google supplants the shopping engines. With a little fine tuning and the ability to filter out unwanted responsed easier, Google will become the last word.