Going through $50's, this guy caught my eye. Of course upon close inspection, it's not quite an error, but oh so close. I'm sure it's still worth a fortune on ebya, I just need to get an SGS holder for it.
dang that IS close!!! another 1/32 of an inch and you would have had something there!!! keep searching they are out there... presumeably
The overprint is shifted to the left. Just another 1/32" and the serial number on the left would be touching a design element it's not supposed to.