I'd be interested to hear if it really worked but I think it's one of those too good to be true. If you got the money to spare let us know what you think. I'll hold onto my money for now and use it to help buy another tank of gas.
Check this Ebayer out and you'll find that he has sold a lot of these in the past several months. But if you notice that all of the buyers have very little feedback which tells me that they have little expierence with eBay. Maybe contact one of them and ask if it works.