Blokarts are made in New Zealand and have a good dealer network in Australia.
At the moment there are NO commercial land yacht manufactures in Australia as it is probably not commercially viable due to the small population compared to USA or Europe.
There is a cheap yacht (Zooter) manufactured but would STRONGLY advise AGAINST it as it has proven very fragile, fails rapidly and is unreliable the importer also seems to have a dubious financial track record..
Australia runs basically 4 classes being...
Class5 (International class)
Promo5 (similar to a class5 but restricted to restrain costs)
Mini Class (a smaller yacht and ideal for people new to the sport) and
Blokart (although it fits into the Mini class it has a good following for one design racing)
My suggestion is contact
www.landsailingwa.com.au/ I'm sure they will be able to help you.