Idk what their county budget looks like, but if they would set up a shop where interested parties could easily buy prints of that mug shot, I would cheerfully bet my favorite nipple that they will be running a surplus for a very long time.
I think they'd pull in even more if the DA were signing them, but I don't see any reason to not offer a variety of signature options. They might even sell some to Republicans if they do a Trump-signed version.