On the more reasonable side, there's this.
https://www.ebay.com/itm/1994-Signat...QAAOSwwwRa7lcf
Population either 6 or 4. (Not sure what D.G. Grade only means)
if it's not a 10 it seems to have settled in the 150-200 range.
So a lot less common to begin with, on-card signature, and a smaller population in a 10. In fact, there are only 22 nines too so not all that common in ether grade. And only 144 in any grade..