Looking at the prices on the facebook page, they start at 5000 GBP, which is about $9000 now. Isn't this getting into the range of dome prices? And there are some Australian suppliers around for those.
For RoR style though - assuming it's not a DIY, it should not be a difficult project for a local competent builder. I think there isn't really enough of a market to warrant pre-designed sheds - unfortunately.
Btw, they do look quite nice.