The ASV is an amatuer organisation. They have a New Astronomers group, beginners loan scopes and other benefits for new members.
SVAA is a more casual group, and certainly smaller. The twice yearly camps are well worth visiting and you do not have to be a member. You can also trot along to Friday night club nights, again no need to be a member.
There is also the Mornington peninsular astro society (MPAS see
http://www.mpas.asn.au/ ) that would be worth checking out!
Malcolm