and seeing you are from oz, they have really cheap pond pressure filters at bunnings, like $100 cheap. wouldn't assume them to be of good quality, but you never know until you see it running. there is a more expensive one that has a u.v sterilizer built in, for around $250. but then my laguna filter cost $300, and thats a rolf. c. hagen brand, supposedly the best aquarium products manufacturer, according to this years practicalfishkeeping manufacturer awards.
edit: that was a quick reply