Bingos are a dying piece of pinball history. My dad used to build them in the basement and put them out on route in Baltimore. That was how he started in the amusement business.
Sadly, people that grew up in that era are getting few and far between, and interest has waned. This is actually good for you though, because you can obtain a bingo machine for next to nothing. The more popular ones are the 25 hole "OK" machines like County Fair, Silver Sails, Laguna Beach, and Circus Queen (and others). I was more of a 20 hole A-B-C "Mystic Lines" fan, because they were easier for me to understand and play as a young kid. The 20 holers were generally built in the late 60's on up. There are also the "6-card" bingos like Nashville and Dixieland, which play just like a game of 6 card bingo (just like grandma plays at the VFW LOL). You can still find an old 6 card on route down south and in certain parts of Pennsylvania.
Stay away from the Sirmo electronic bingos. They are a pain in the rear. Learn how to worn on an electro-mechanical bingo. Like a previous poster said, it is satisfying to get one in and get it running. Of course, satisfying can be considered code for 'difficult,' but hey, what's the harm in learning about a lost art?
-Mike
