well, after many years of thinking this was a fruitless quest, today I happened across an Australian supplier who apparently will supply 1/3 cut (and also 1/5 cut) file folders in Australia with free shipping in Oz.
From what I can make out from their web site:
and their File Folders area:
http://www.fishpond.com.au/Stationer...s/File_Folders (do a search on 1/3 cut to see lots of goodies!)
they appear to only have US Letter and US Legal size at present. I've emailed them to ask if they intend to stock standard A4, and let them know about this group of Aussies who would be quite happy if they did!
Will keep you upated on how this pans...