If you are serious about starting an Ebay business, as a business, and not just as a casual hit or miss listing venue, then you need to learn how to do some serious market research. Even within Ebay itself, you can conduct your own market research. Here is an example. Suppose you like to fish and you want to start selling fishing rods. To find out if it's even worth your time, you need to see how many others are selling fishing rods on Ebay. . . not only how many others are selling fishing rods, but what kinds of fishing rods. If you know of one or two very special types of fishing rods, then research that instead because you may be able to develop what is called a "niche" market around a few really good and profitable fishing rods.
Make sure you login to your Ebay account. Go to the Ebay search bar and type in "fishing rods". Look at the results. How many do you see? Do any of the listings have the type of rod that you want to sell? If not, then maybe you can get a captive market by selling your unique rods. Next, look on the left side menu. Scroll down until you see the words "completed listings". Click on enter again and now what comes up are all of the fishing rods that have actually sold and how much they've sold for in green numbers instead of black numbers. That gives you a clue as to whether or not you will make any money selling your fishing rods.
There's lots more to market research then just this, however, this is a great start. I had to pay hundreds of dollars when I first started on Ebay just to find out this basic information. Hopefully you will put it to good use.
Outside of these basics there are companies who specialize in helping you to do market research. These are the types of companies you will want to contact when you get your feet wet and really want to start growing. Companies like "thinkpassenger.com" will help you with your online market research. This unique market research company helps you to bring your brand to market through social network sites and other social interaction. They can take your product and identify the best places to share the information basically at the speed of light. Each client has a program tailored to their own needs. This step is when you jump in feet first with the big boys and play with major brand name companies.
Market research is critical to success when building a serious business online and you should use every tool available at your disposal.