I didn't bother with a test kit when I cycled my tank. My LFS does as
many free tests as I want, and they're not too far away from my home.
You definately need to test your tank regularly in the setup stage, but
less frequently once the tank is established (once you get into a
routine eg. how much water to change, how often and how much food to
feed, etc. etc.).

Maybe some test strips would suffice as a rough guide, then get your
LFS to do the rest. If your LFS won't test your water for free, find
another LFS.

If you want to buy gear online at reasonable prices, try these guys...
http://www.equarium.com.au/ I bought my filters there, and other
start-up supplies, and found them to be good to deal with.

Where in Australia are you?

Also.. I had small oscars once... they didn't stay that way for long! I
hope you're prepared!