I actually looked up the exact kit you mentioned and you are right, it's actually a pretty decent deal for a kit.
For reference to others who are reading, $400AUD is about $270USD and the kit includes a stand, light, filter, heater, and lid. Just doing some of my own searching, buying equivalents separately in the US market would come out to a bit over $270USD, so the kit seems a pretty good deal actually. Of course, getting used goods is still way better, cost wise, but it sure is a pain having to hunt down everything separately and keep track of all the different sellers. So yeah, go for it if you can, elephantnose! I hope your parents will allow you to have a larger tank if you pay for it all yourself.