eBay has their own Market Research area that includes loads of information and market research analyses. This is a paid option but you are sure to find valuable information here http://pages.ebay.com/marketplace_research/index.html. You can pay for a one-time only usage or subscribe by the month.
Alternatively you could try the free tool available called eBay Pulse. It contains several lists showing popular searches, stores, products, and more. These lists are a great way for you see what is hot in the eBay marketplace. You can find it here http://pages.ebay.com/marketplace_research/index.html
You can also do some things your self and to get a feel for what may sell, click on the BUY button at the top left of any eBay screen. The link will reveal a plethora of categories of items. Find some categories that you are interested in and go from there.
This is where you can start to refine your search somewhat, for example you can select to see the higher priced items first in the search list going down to the lower priced items. You can also dig a little further with your search to show only completed auctions, this will give you a more accurate picture of what items actually did sell.
Finally if you merely want to see if the widget you have sitting in your garage is hot, type in the name of whatever it is in the search box and see what comes up. You may be surprised to find that it is selling for $100 or you may find that there are multiple listings for the same widget yet no one will enter an opening bid of $2.99. That will surely tell you something about that widget and if it is the right thing to sell on eBay.
It is one thing to see current auctions, however since much of the bidding doesn’t occur until the final few minutes, it is better to look at closed auctions. Then you’ll see if your prized import Teddy Bear is really worth anything. Or you’ll see that your old baseball cards had 23 listings and not one of them sold.
The bottom line here is research. If you want to find out what are the best selling items on eBay then do your research, it will always pay off in the end.
For more help with selling on eBay have a look at Secrets To Profitable Auctions – List Like A Pro.