Another vote for Jeans West maternity jeans. I lived in them throughout my pregnancy.
As for other maternity wear, I bought it from the US - the AUD was much stronger last year, so it may not be as cost-effective now. I bought from Old Navy - jersey maxi skirts and maternity leggings as well as some maternity tops. I bought nine pieces for AU$120 including shipping. But as I said the AUD was a lot higher then than it is now.
Next do have good maternity stuff. I reckon it's worth taking a look. If you spend over $30 then shipping from the UK is free. And they are really quick to send (5 working days and you'll have it).