There are a lot filters around. The Eheim Ecco filters are cheaper, but the build quality matches, they introduced the Ecco range to compete with the Fluvals, frankly I believe that was a mistake, people buy an Ecco, have trouble with it and assume Eheims are bad. An Ecco 2233 would do.
You might get away with a Fluval 204 although a 304 would be better, depends on your stocking level, a heavily stocked tank needs more filtration. I've always found Fluvals fiddly to use, they seem to have an inevitable slow leak. They are probably better now, but 15 years ago, you needed to keep the filter inside a bucket to catch the leakage!
There are dozens of other makes, not all are available everywhere though. I don't know what else would be in the shops/mail order in Aus.