Some Health Food Stores stock Melrose AJC which I have used, but it isn't cheap at about $10 for 360ml. Otherwise make your own. There are posts on here about how to do it (basically freeze the AJ then collect the concentrate as it thaws before the ice starts to melt).
If you are after preservative free juice to make AJC (or cider), try Bellevue Orchards "Summer Snow" juice. They are in Officer, Victoria and deliver straight or mixed juice at about $45 for 12 litres.