Been making my own for years using Kefir .... actually the Kefir makes the yoghurt, I just add some fruits like raspberries, blackberries, grapes etc.
It's fair easy to do and takes less than five minutes a day to produce as much or as little as you want.
Just get yourself some Kefir milk grains and in no time they grow and double in volume. I paid about £2.50 for mine and they are still producing 5 years on.
Readily available on ebay, for all sorts of prices and will start producing from day two ... search for :- kefir milk grains.
The Actimel you see advertised on TV has live bacteria ( the good kind) in it, but it's a few days old when you buy it. If you make it yourself, the bacteria couldn't be fresher. All you need to do is add the milk, I prefer whole milk, it makes a thicker yoghurt. After you have strained the Kefir, just put it in the fridge overnight and then add fruit juice to the milk drink .. or fruit to the yoghurt.
Apparently it has all sorts of benefits, but I just like it for it's taste and look forward to it every morning.
The info on how to use it is readily available.