I have returned only two in about 200 purchases. Make sure the image listed is the same as item on auction. Many sellers will reuse an image of coin without any indication to sell many of the same type. When Yahoo auctions was free coins were listed more expensive than on ebay since the lack of buyers on Yahoo makes most items sell at the opening bid. If you are the only bidder on Ebay then you need to be sure of the market value.
Some sellers start low which attracts bids and establish the value.
Some start high and reduce only if they don't get any bids. I now have much more patience. If you look over a long period you will item you really like, with an authenticity you can trust, at a price you can afford. But that process is far more expensive time wise, but then is part of the joy of collecting. Feedback Ratings Feedback is supposed to guide you when bidding.