RA4 chemistry is being produced in massive quantities, and last time I was in a brick & mortar shop here in Europe (a few weeks ago), plenty of small Adox 2.5L kits on the shelves. So just ask your favorite retailer(s) when the stuff will be back in stock again and pre-order if so desired.
The situation with Tetenal and Kodak may be different from other brands; Kodak chemistry (SinoPromise) is pretty much M.I.A. at this point and it's uncertain if, how much and when it'll return. Tetenal I'm also not sure of, but do a search here on the forum and you'll find some threads discussing the present situation.
Adox is running full steam ahead and Fuji are also producing chemistry by the truckload, so surely, some of it will even trickle down into Australia.