It looks like they may not be in business any longer. I did a pretty thorough online search.
I did however find a few finished sales on eBay. I would recommend doing periodic searches there to see if you come up with anything. eBay has quite a few shops that offer muumuus so you might also find an alternative that you like.
I'd also like to recommend you check out Big On Batik --> http://www.bigonbatik.com/
There's another one I wanted to recommend but the name is escaping me at the moment. If I remember it I will post it later.