Quoted from John_I:I would avoid Data East if you are wanting to learn to maintain a machine. Go with the JM. You should be able to find a decent one for $3500.
I actually kind of hate JM, and wouldn't wish it on anybody! It has a lot of good things going for it for sure, but it can be so unfair/unfun with side drains and very clunky shots. Plus, the hand is a PITA. Even when it's working all right, it's still a finicky bastard. I love the video mode though. I owned a JM for about 6 weeks and couldn't sell it fast enough.
But some people love JM, so to each their own!