I make my own yoghurt with an Easiyo maker. You can get them at Coles supermarkets. Only about $3 for equivalent of 1kg. I agree with the others on getting the natural yogurt, if they don't know any different they won't complain. My DS loves natural. I just make sure it is the full fat one.
Hi Kylie! Thought I'd look you up.

Just recently found out that you can make your own yoghurt WITHOUT the bought sachets with the Easy-Yo maker. The trick is to use UHT milk instead of fresh. This makes sense, as apparently traditionally you quickly scold the milk before you make yoghurt with it. Have heard biodynamic milk works too, but not sure why! Rough recipe: 2/3 cup your favourite natural set yoghurt (try good greek yoghurt or Jalna) plus 1 Litre of UHT full cream milk. Cap and shake to mix. Place tub in the outer container with the boiling water and leave at least 8 hours/overnight as normal. Use a bit more yoghurt next time if too runnny or leave for a few more hours. Can use the yoghurt to start the next batch. Not sure how many times you can do this safely, but assume 2-3 months would be okay before starting with fresh yoghurt starter again as yoghurt as such a long expiry date. Best of luck to all who try it!