I've been browsing and I found a seller on eBay named "bogotana" with a large feedback number (which doesn't mean he is legit..or bad by any means, as the signatures should always speak for themselves).
http://myworld.ebay.com/bogotana/
He has about 6 dozen items, most of which I am not experienced with regard to their authenticity. Here's a Travolta he has for sale, I am not interested in it and I dont know his signature, but maybe someone could draw an opinion on the seller based on this item as Travolta is ubiquitous. He also has a J Leno, Michael J. Fox, and a Woody Allen.
Here's the Travolta: 
Thanks! -Mike