Ebay used to have great deals. Because of that, the initial users spread word about said great deals. More users flocked to the site, and sellers began to see a chance to take advantage of them. Anymore, I've all but stopped using it, because as someone said, you can get the stuff cheaper elsewhere.
Not to mention most Ebay sellers are members of the "Pricewatch School of Shipping Costs". I just had a friend buy a sound card from ebay, he paid $10 for the card, $8 for shipping. He got the package, the shipping label said $3.95. And it was packed in Priority mail boxes/supplies (read: free from the post office). Any decent deal is usually offset by the high shipping cost.