Well, imagine if you bought a slot machine and just played it for fun. It's sort of like that but with a bit more interactivity. They're much more interesting from a historical perspective.

Also, figuring out the rules and odds is kind of interesting. Some of them are ridiculously complex - I think way more complex than slot machines of that era.

Most will let you buy an extra ball, and often multiple extra balls. However, the EB is not guaranteed. You can "wager" a credit and there's a %chance you'll actually get it, and I think the %chance goes down with each additional extra ball you want to buy. A few times I had to spend as much as 20 credits to get an EB. So you're gambling on how many credits you'll have to waste to get the EB and whether it's worth it given your most likely payout (assuming you make the shot, of course).

The credits aren't like free games in modern games. I racked up 80 credits on a game recently. Then I used up 60 on the very next game.

They still make bingos. They make them in China and it appears they're mainly sold to central and south america.

I contacted a distributor and learned they cost about $500 each, and shipping was around $550.

http://www.youtube.com/watch?feature=player_embedded&v=BEJ2vE8dw8Q

Bingos tend to go for very little. $50 - 200 is typical. I have been offered a few for free.