I live in Turkey where yogurt is an essential part of our diet and culture and nothing beats a homemade pot with a thick layer of cream on top.

I can assure you, you'll never need to buy any more starter, ever! As long as you save some for the next batch, you're golden! If you can use unprocessed milk purchased directly from a dairy farm, that's even better as I promise your tastebuds will rejoice! :)