Are we taking about the seller from Buenos Aires? Good luck contacting the local authorities there. He keeps his buyers ids secret so we can't contact them and tell them their fakes. The other problem is Ebay has a policy that you cannot interfer with another sellers transaction. It could get you banned if you warn the buyers. I think the best way is to contact the buyers who leave feedback and just ask them if they know if the sign they bought was a repro. Give them the dirt, the link to this forum, let them figure it out, and let them file a claim with Ebay. Seller will get banned, get a new id, and start over again. Very difficult to remedy.