Search though "Equipment and Where to Buy" in here:-
http://www.iceinspace.com.au/links.html
I can recommend the Bintel shop in Camberwell, at 519 Burke Road.
York Optical are in the city at
114 Flinders Street.
There are a few others in Melbourne.
Several people are happy to mail order from elsewhere around Australia, eg. from Andrews Communications.
Carefully compare prices, options included and after-sales service.