Fleath, I was in Vanbar's last week and enquired as to whether they still had any in stock. A check of their computer revealed no stock in Australia. I think I bought about their last 400 sheets a few months ago, it was very old stock, like about 8 years.
As CR Kennedy the importer of Ilford product, refuses to import Ilford Postcard stock, unless there is any old stock in Australia, you will not be able to source any inside Australia.
I bought 1,000 sheets from Germany a couple of years ago, I'm almost through that lot and I think I will just cut up other stock to size for the future.