I have only seen two come up for auction in the past few years. There was a baseball in the last REA auction, but it was traced over, and appears to not have sold?
http://www.robertedwardauctions.com/.../2013/935.html
And there is a t206 card laminated and slabbed by JSA.
http://sports.ha.com/c/item.zx?saleNo=716&lotIdNo=61001
I have probably missed several and, like you, would love to see any and all examples that people can show or provide links to.
As with any auto this rare, the authenticity of these items is quite hard to determine.