Always keen to help an Aussie but I haven't seen these for sale in my travels.
I recently made my own speaker grills from MDF and covered them in speaker fabric which I purchased from RS Components in Wetherill Park, Sydney. Their stock number is 250463 and the fabric cost $16.00 + delivery.
The job was a little fiddly but I got reasonable results. Might be an option if you are stuck.....