Nice 02, a pretty rare set up I imagine in Aus.
There are a few places to get parts, such a panels. I would recommend Ash Sprague at Brighton BMW, 02 enthusiast and Bmw spare parts guy. Particularly helpful for big/precious items where you don't want to have to worry about shipping, however, you do pay a premium, as with most things in Australia, supply/demand etc.
That said, Steve at Blunt industries in the States is pretty sharp with his prices, quotes within 24 hours, and reasonably priced shipping. He has a stellar record with helping me with parts.
wallothnesch (google them) are pretty good, but you need to spend a bit before it makes it worth while. Although with our dollar on parade with the US it makes it hard to go past Blunt.
Also there is the local 02 Register which is helpful/friendly way of finding secondhand (sometimes new) parts.
All the best.