Here's the deal. There really isn't an alternative to eBay. You can dream all you want but if you want to sell anything you will put it on eBay. If you don't it won't either sell or you won't get anything for it. There is no competition. Yahoo tried but it died an early death.
Put it this way, you have a super rare card and you want the most exposure, where would you want to auction it? I'm thinking there isn't much argument here.