I just started making my own yogurt a few weeks ago. I used the starter that came with the YoLife "incubator". It was okay. I'm using a starter I found at Whole Foods now, and I like it just fine.
Two things I've learned: soymilk makes terrible, thin, chalky-tasting yogurt. Grapefruit does NOT make a good add-in flavor to soymilk yogurt. Blech.
Did you see Harold McGee's piece,
They Do the Work, You Reap the Yogurt, in the NYTimes?
Haven't tried using store yogurt as a starter yet...that's next batch.
Is straining in cheesecloth the best way to get that thick, Fage-like consistency?