You can make your own yogurt. I do it often. I use either a commercial yogurt with a live culture or with a dry yogurt starter called Yogourmet.
If your yogurt turns out kind of stringy-slimy, it’s gotten some other strains of bacteria in it. I don’t know if it’s bad for you but I don’t like it so I used to toss it out when that happened occasionally. It used to happen when I used homemade methods for keeping the yogurt hot but since I bought a yogurt maker, it is rarer… or maybe it hasn’t happened at all, come to think of it.
I’ve had mine for five or six years and seems as good as new, so it’s a good investment.
Recipes often call for sweetener and powdered milk but I use neither.
I like not supporting the plastics industry by not buying all those tubs, and buying the milk to make the yogurt is way cheaper than buying yogurt. When I’m rushed I don’t tend to make a lot of yogurt, but when I have time, I do like to do it.
Here are a selection of yogurt makers. The one on the right is my favorite.