I like using the yogurt of Sky-Top and Fage brands as a mother culture. When I don't have it, I use a brand of culture called Yogurmet which you can get at Whole Foods. Very tangy and when strained it's a perfect greek yogurt. Leave it out starining covered with a cloth for another day and you get Labaneh cheese. There is a brand of yogurt makers Euro Cuisine - they also sell culture under their brand and you can find it easily online on eBay and Amazon. I am almost sure that this is the same as that Yogurmet because it contains the same bacteria collection, tastes the same and the package looks the same just with different brand printed on it.
I just got a pack of "Y5 Yogurt Culture" from New England Cheesemaking but have not tried it yet.
