Yep, make 4 litres per week. Cheaper and way better.
That link is way too complex though. I bring 4 litres of milk to the near-boil. Take it off the heat and let it cool until you can just touch the outside of the pot with your inner forearm.
Sterilise tupperware - just put boiling water straight from the kettle into the pots, then turn upside down on a dishrack to dry
Mix starter culture (about 100ml), a splash of vanilla, and a tin of powdered milk into the milk. Put into the containers you've already sterilised
Put in an esky. I add a couple of litres of boiling water in a container into the esky to keep it warm, but I'm in tasmania. In a warm place this isn't needed.
I mix it in the morning, and get it out when I get home from work.
If you want runny yoghurt, let the milk cool to room temperature before mixing in culture. if you want it thick, put it in at the temperature I said here.
First batch, get your culture from a high quality natural yoghurt - I recommend Jalna. Don't go farmers union - their yoghurt's nice but the culture gives your homemade yoghurt a slimy texture
Thereafter, some of the yoghurt batch you make, put it into a dedicated small container. Never eat from that small container - keep it clean so you don't contaminate your culture.
If you don't want 4 litres, just make a smaller batch
Total preparation time 5 minutes, but need to have good timing to get off the heat, and to mix the yoghurt when it has cooled to the right temperature