Hey mate, fellow aussie here.
I'll just be honest and say those bikes (cyclops/avalanche) umm aren't really going to show you the true nature of mountain bike riding. The main reason for that is they are really not built for off road use. After a few rides they will more than likely self destruct. They are also extremely dangerous if you start doing anything other than riding on a flat dirt ROAD. You've obviously had a taste of this awesome sport/hobby and to be honest you are probably yet to experience the REAL pleasure of mountain biking and why its one of the fastest growing sports in the world.
If I may make a few suggestions in regards to suitable bikes;
In Australia, the brand GIANT is almost everywhere! They not only produce great entry level quality mountain bikes, they do it at some of the best prices in the country. Brand new, their entry level mtb ranges from about $650 - $1000. Which I understand is twice your budget but theres no comparison really. It will feel like a Ferrari after getting off your cyclops.
If you dont mind buying second hand, do a quick google on australian mtb clubs. Most clubs have some form of classifieds on their website where riders are always getting rid of their entry level bikes. You can usually get a STEAL because people need to sell before they can afford their upgrade. For example my local club CORC http://new.corc.asn.au/classifieds/?IntCatId=16 has a classifieds page that I usually check everyday for bargains.
To help with your terminology, if you can manage to find a HARDTAIL (name for a mtb with front suspension only - much cheaper usually) with quality entry level components SHIMANO DEORE or SRAM X7 second hand with a FOX or ROCKSHOX front fork, you'll be laughing.

If you'd like any particular advice on particular bikes or any advice all round on mountain biking in australia feel free to contact me through my profile or blog.