Well here in the UK I use
www.sospubs.co.uk or
www.rlmusic.co.uk to source old analog synths. Availability is good. For people in australia....Id say you should go look at Japanese specialist dealers or online auctions...
There are alot of SH101's, Jupiters and Mono-Poly's floating around over there. Here back in the UK they are a little lighter on the ground. We tend to get more of the American manufacturers i.e. Sequential.
DS