$0.50/3 plays per dollar. We've been doing it this way for 25 years and the games bring in nearly $400/week at our main location. Nobody complains about price, I regularly see the same person putting a handful of quarters in a single game. It's profitable for us and good entertainment for our patrons. Older DMDs and alphanumerics, nothing beyond 1995.
I've been to an arcade run by actual pinheads who have recently developed an attitude for not fixing major issues with their games. That's not going to fly with me.