If you are going to start an Ebay business and you want it to be successful, you must choose a market niche. A market niche is not golf, hunting, cars, clothing, etc.. That is a market segment. A true ebay market niche digs much deeper. Lets take golf for example. Golf is very popular and there is lots of money to be made online. If you try to compete with just "golf" being your true niche market, you will never get anywhere close to the first page of google any time soon. How about "golf clubs"? Same thing. . . it won't get you near the first page of google. How about "Arnold Palmer golf clubs?" Now you're getting closer to a true market niche.
What would you think about "Arnold Palmer golf putter"? Drilling down, down, down and making the market niche the smallest you can get it so that it still has traffic is the way to go. Find your distributor and use the right keywords to get yourself on the first page of google. Become an expert in that niche by writing articles about the putter and watch yourself get closer to the first page over time.