I'm not a doctor nor particularly fond of them, but as I understand it older men who have been sexually active are likely already exposed, so doctors won't prescribe the vaccine nor will insurance cover the cost. I don't know if it's something you can just walk in to a clinic and ask for and pay cash.
The big push lately has been to get kids vaccinated before they are teens, which mine (all males) were.
I have not had this vaccine, but at my age and being married any new sexual contacts are pretty unlikely so not sure there's any benefit to me either way.