I think they just didn't make too many of them. I've been on the lookout for a while too, there was a 27 and a 30oz, I think the 30oz is still available. But I am sure there are plenty of members on here sitting on a stockpile of them. . . . I have heard good things about them too, and I am dying to try one, but i don't know anybody with one so I am forced to buy one.
p.s after you've been on this site for a while you will have more than 4 bats, it's addicting. I have 8 and I am really battling myself not to buy more. haha, so 4 isn't bad at all, and compared to most people on here 8 probably isn't bad either.