Nowadays, most people who offer a product for sale obviously offer it on the Internet. There are plenty of very good product search resources on the Internet, and the few listed below are, as one would expect, absolutely free.
Product search services are much more sophisticated and easier to use for the general public and typically don't use elaborate Boolean search strategies, like we were forced to use in the "Do It Yourself Patent Search" on the PTO's website.
For a typical product search on the general internet, you'll just want to limit your search to your main noun (and any relevant synonyms) and one or two distinguishing concepts.
Try your search on a variety of search engines, not just Google. You can search many of the search engines at once using Dogpile, Zoo, or WebCrawler. Or individually use search engines such as Bing, Yahoo, Alta Vista, LookSmart, Lycos, HotBot, AOL, etc.
You should enclose your search strings within quotation marks to force the search engines to return only pages that have that exact phrase. But be sure to try a variety of search strings (as shown above) since not everyone will describe the product in the same way using the same words. Again, this process hit or miss for a non-professional, but if you get a quick obvious hit, it can save you time and money by not needing to hire a professional.
If you still don't find anything that would likely pre-empt your potential patent after your own hard work of searching, that's a good sign. But, unfortunately, that doesn't mean you are home-free. At that point, it's time to call in the experts at QuickPatents.com to look under all the rocks to see if there are any relevant patents hiding under them.