They are my pride and Joy, I am not lucky to have dug any intact but I've been fortunate to have found several, been gifted a few, and purchased others with marbles inside. I have become a marble lover from the joy of looking through all the different types.
I'm not naturally a jar collector, but I have gotten a few nice ones over the years. Some common, but I have heard the short jars are scarce. I have no idea if they really are though.