My guess is that a seller in this situation could plead ignorance ("well that's what I was told when I bought it") and eBay probably has the "let the buyer beware" attitude, and won't do much, if anything.
Unless it's a totally phony ad, where the seller doesn't actually have the item, if eBay is going to make a little money they may not care. That may sound cynical, but hey. It's all about money, power, and somebody being able to buy a big-screen TV. Everything will be all messed up until the Vulcans land and fix everything.
I do know eBay gets after sellers for high postage rates though... like a 99 cent item with $20 shipping... eBay doesn't like that, because they can't make money off of postage.
I did have luck pursuing something through PayPal's really boring and involved process requiring faxing of documents-- I *won* and could have gotten my money back if I'd returned the item to the seller who misrepresented it. By then, I had invested in fixing the item and it would have been foolish to send it back. Lesson learned: see what the seller usually sells. If it's used computers, don't let him pretend this was his little personal laptop.
Peace and Long Life
Kathy