If you’re thinking of picking one of these up at some point, now is the time to do so. Currently, there is a whopping ten of these on eBay. Since there’s only a limited market in people who will want this for collectors sake, having ten up at one time should keep the prices a little lower.
Apparently, my initial info was wrong on this as well. Several sellers cite that there was 110 of these made, with 55 featuring Batman and another 55 featuring the Joker.