Market Research For Your Invention Idea
To find out if your product idea is already on the shelves or if similar products are already available, start first with a simple search on google.com and bing.com. Try to use a large variety of words that could be used to describe your product idea. Also, do a search on Amazon.com and Walmart.com and other product sites that would likely carry your invention if it was already on the market.
If you don't find anything after doing a quick search, then proceed to conducting a more extensive search including a patent search and doing the necessary market analysis. The resources below may help you start your research:
Helpful Articles from InventorSpot.com
Industry and Market Analysis for Your Invention Idea
Hoover's Online - Online Business and Company Information