I've bought a lot of fabric on ebay and had it sent to my mom. Usually I am super pleased as the fabric usually looks better in person than on the computer.
But I have been basically stash building and buying themed fabrics. I don't remember ever being disappointed. If you buy "lots" you can get very good prices. This is great for the person who just wants to have a variety of colors and fabrics. If you are super picky, then you should go to ebay knowing already what you want and just search. They have just about everything eventually!
But if you don't shop there, that will keep the prices cheaper for those of us that do! ;)