People find the prospect of making their own yogurt daunting but it's surprisingly easy and really just takes a bit of experimenting with your microwave and yogurt maker to get it perfect. You will get instructions in your maker which can be purchased in either 1 or 2 L containers and then you can make a few changes on your own from there. Most will tell you that it is crucial to get the temp right and how important it is that all utensils that touch it are sterilized but this isn't true. No biggie and once you try your own you will not buy the store stuff again not to mention how much cheaper it is. I estimate that it's a 1/4 the price.
Measure out either 2 cups for 1L or 4 cups seen here for 2L in a microwave safe measuring glass container and microwave to the temperature your maker tells you.
Once your milk has heated to the right temp you can add approx 2/3 cup dried skim milk powder along with about 1/2 cup of of your last homemade yogurt or a store bought brand as long as it has live culture. Stir until dissolved.
Now add mixture to your yogurt maker and let sit for 8-10 hrs after which you will refrigerate until cooled.
If after your yogurt is chilled you would like to make greek yogurt which is simply removing the liquid whey to make a yogurt of 'cream cheese' consistency, just put a coffee filter into a strainer and let your yogurt drain for about 3-4 hrs.