Coin Operated machines can often produce the cheapest of souveniers and shortest of waits in the park.
My favorite? "Fortune Red."
It's been there every time I have, it's price has never increased (still 25 cents) and always produces a cool Pirates of the Caribbean card. Last time the sound wasn't working but I still got a card out of it. Hopefully Red will continue to be looked after as well as it has been in the past.
Honorable mentions: Shruken Ned and Indiana Jones: The Pinball Adventure.