I'm with Fred. The numbers of errors compared to the mintages of these coins leaves little room for finding any. Add in the time spend and it's easier to buy them. They really aren't that costly.
I can understand your point, Fred, but for someone like @Mountain Man who lives in the boonies of Montana and is likely snowed-in for months on end, it is probably a good way to pass the time. By the way, anyone who asks what the odds would be is a fool. If you're doing it for the enjoyment, you never lose.