Not rare, but hard to find? Doesn't rare mean hard to find? Sure they might not go for a lot of money because there's no real demand, and I'm sure they turn up more in Japanese circles, but it's still something most people are never going to run across.
And I meant more the entire box/station setup, not just the cart.
But in any case, it was an interesting thing to learn about, so that's what really matters.