http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l25...

This crummy little forgery sold for $87.50. It has a GAI sticker and a certificate of authenticity from Piece of the Past signed by Kevin Martin.

I'm not sure which would give me less confidence in the authenticity of an item. One accompanied by a handwritten note from the signer stating the item is not authentic or having it be certified by GAI and Kevin Martin.