Googles search engine for finding products is now called boringly product search as a feature of google rather than a stand alone product.

It uses the same look and feel as the web search and allows you to search on keywords but then filter down the results against price and venders. There is 4 different ways to sort the results as well which includes relevance, low->high, high->low, product rating and seller rating.

The last two are about collaborative quality filtering where google is taking the opinions of a large number of people and ranking the results based on previous experience. In this line of data mining google is very good and the results are likily to be better than a smaller site like kelkoo.com etc.

The one thing to watch out for though is that some of the links will be listed with the ex VAt price to get a higher ranking and others will include VAT in their listing. This is to be watched out for so you do not get stung on trying to buy the product.

My experience though is that to keyword search for a product you are looking for is hard and you get a lot of results on products you are not interested in or for sources you do not want to buy from. For this reason I tend to just use the normal google search functionality then use the search functions on the retailer sites I arrive at.