Buyer beware everywhere. I use ebay all the time, and have had no problems. If you don't research what your buying anywhere, local or the web then you have too much money. Example: If you want a cps for your truck, there are many different ways to get one, many different prices, and quality of product. I bought my grill off ebay because it doesn't look like everything else on the road, and it is the only place you will find it. I bought my grill emblem off ebay, because it was new and $12 shipped, never even checked the price at the stealership because its $12. You have to know what you want and how much its worth.
The one thing you have to watch out for on ebay is false bidding. There are too many people that have their friends drive the price up for them to get you to keep outbidding, because its only a few more dollars. I personally use another site that I put my bid in on, which never gets posted at Ebay until there is only 2 seconds left on the bidding. I just list my max price days ahead off the ending, let it do the rest. If I don't win the item then it's because it went for more than I thought it was worth. Lets say item "x" is listed for $10 and it's worth $50. If there is a bid for $11 then I'm wasting my own money bidding at $12, the dude I'm bidding against knows it worth $50 also, or even worse, he's buddies with the seller, or even worse, he doesn't care how much, he just wants it. The best case scenario is that the dude that bid $11 is the only bidder and has his max set $20. I put my info on the site I use and set my max at $50. With two seconds left my site will out bid him at $21 with no time in the auction for me to get outbid, since the process takes about 5-30 seconds to complete, if you're even at the computer at the end time. I get the good deal, or I don't waste my money. I like ebay, but then again I know the tricks.