I called arcade places and ask the manager who owns the games. It was usually some offsite arcade vendor person who brings in games and maintains them for the business in which they are located in (ie: Putt Putt golf place, bowling alley, etc...) and then the vendor would provide a percentage of the profits with the company owning the location.
I would ask the manager for the phone number of the vendor and then call the vendor directly. They usually have some old games lying around they know are not making them any money anymore so perhaps they would sell you one. If they do not, always ask for references to other vendors (ro anyone else they know who might have arcade cabinets). I usually found a few more good names which I would never have found in the yellow pages, or anywhere else. Most of the people I dealt with end up having storage units with arcade cabinets inside. They would meet me at these storage units and let me look around a bit for something I might want.
I would also call every "arcade" and "amusement vendor" listed in the yellow pages and listed in Yahoo Yellow pages in cities which I would not mind driving to. I would not focus on "main" cities only, since little cities tend to have a lot better deals in my mind. The big city people might try to get more money out of you, but this is my on opinion really. Not to say you cant find a good deal in the bigger cities, I would just try the little guys as well.
Good luck.