You could give them free-round trip plane tickets to anywhere in the country! Oh..wait...that was only the fans at the last Dallas Mavericks home game of the regular season....
I say go with the ring pop idea or be creative and create a refrigerator magnet that either has a fake ring on it or some spangles and jewels as a momento that will last a bit longer than candy. Make sure the title of the show is on there as well if possible.
"You pile up enough tomorrows, and you'll find you are left with nothing but a lot of empty yesterdays. I don't know about you, but I'd like to make today worth remembering." --Harold Hill from The Music Man