This article is from the Model Rockets FAQ, by Wolfram von Kiparski with numerous contributions by others.
There is at least one national-level body now in Australia. It
covers both model rocket and HPR levels. The body is :
Australian Rocketry Association
PO Box 125
Oaklands Park SA 5046
EMAIL: email@example.com (David Sakko, Vice President)
Membership is $25 per annum, and an additional $10 per annum per
additional family member. Minimum age is 8yo and membership includes
insurance, a quarterly newsletter, ID card, and guide book.
Sport Rocketry is available through them at $40 (surface) or $92 (air)
The association is also working with the CAA, state governments and
the AFPA to standardise regulations and to obtain better flying
Also, there is at least one model aircraft club that welcomes, but does not
cover, model rocket launches. For the scale modellers, there is also an
active Astronautical Society, who can provide a lot of information,
and are well worth joining if you are interested in the world of the
"big stuff" as well.