After 5 years of searching, I finally have him: Caligula. Fourré denarius, Lugdunum (Lyon) mint, 40CE. Reverse: "SPQR - Ob Cives Servatos", "PP"

If you mean in contemporary value, a denarius back then was a day's pay for general labor.

Today, denarii of caligula go for many thousands of €. This is a fourré, which is essentially a contemporary fake, and these are significantly less expensive, "only" hundreds instead of thousands.

Yes, there's a small hole at the bottom of the neck through which you can see corroded copper, and a larger hole in the portrait's hair, showing the same. The weight is also lower than it should be because only the exterior is silver. The weight is the only way to identify them if they don't have surface faults like this one does.