Does anyone know where in Australia I can buy a hobbyist PCB etching kit from please. I have tried all the usual suppliers but to no avail. I would like to learn to do tis for smaller PCB or replacement ones.
I'm going to repeat what everyone else has said: Do you really want to bother? I'll explain why below.
Back in the day (like 35 years ago), I used to use ferric chloride you could buy at the local radio shack (in the US). You could buy bare copper clad circuit boards. To do the resist you'd either use rub on trace transfers or in some cases I'd just draw my traces with a sharpie.
When laser printers became readily available, I graduated to using circuit board design software and printing the design on an overhead transparency (i.e., clear plastic). I'd then use that transparency to expose a photosensitive circuit board. You'd then need a developer to clean the excess resist off before etching. About this time I switched to Ammonium Persulfate as my etchant as Ferric Chloride likes to stain when spilled.
I never ended up with a fancy etchant tank - it was always a plastic tray that I'd manually slosh the etchant around. After that was done etching, You'd then have to drill all the holes - maybe this isn't as big of a deal anymore with surface mount, but that was a time consumer since everything was through hole components.
I quit before figuring out toner transfer - apparently that works fairly well as it basically uses an iron to transfer toner to the board. You still need bare copper clad, but then you're ironing your design onto the board, and using the toner itself for the etch resist.
So why did I quit? Quite frankly, all of the above is a big PITA. 30 years ago you didn't have much of a choice. Today, you download KiCad (free). Do your design (time), and then send it off to a fab. The cost for 5 boards delivered isn't much more than the cost of bare copper boards, and when you factor in the cost of etchant and everything else, you're going to find that it's just simpler and easier and most likely cheaper to get the boards professionally done.
Now, if you're looking to do it so you can say you've etched your own boards for some reason, that might be a different thing. Personally, if I wanted to make my own boards I'd probably look at doing the "cnc router" method since I suspect it would be about the same cost to build one of the mini CNC kits ($100-150ish) as it would be to get everything you need to do old school etching. I believe those do the holes as well if you need through holes.