Quark is similar to sour cream. You can make your own using purchased buttermilk.
Labna is a cheese made from yogurt and has been made and consumed since Egyptian times.
This recipe from the GutsyGourmet.com is for making your own Armenian Yogurt at home is . All you need is whole milk and yogurt starter or, commercially prepared yogurt from the grocery store.
Recipe from the Traditional Greek Cooking by George Moudiotis. Greek style yogurt is thicker and creamier with a higher fat content than typical yogurts found in the U.S. Typical fat content of the cow's milk yogurt is 9% as opposed the U.S. yogurts are less than 4% fat.
Labneh is a Middle Eastern Yogurt Cheese. This is easy to make at home with store-purchased yogurt. Labneh is served with a good quality olive oil and Zaatar herb mixture