I don't really have a whole lot of experience, but, this is my opinion on it...
If you are going to spend money on your initial investment (to get the products to sell on ebay) you are not going to see a very high profit margin...
not to mention the amount of niche stores have exploded and the competition is through the roof now...
If I were you I would focus on another project...
However, if you do go for it - good luck and go big or go home... finding a profitable niche is going to be tough, just as it is with websites, but they are out there and there is a demand for little trinkets...