They sell a yogurt starter that is purportedly Salivarius and ruteirii culture over at Beazos' Clubhouse. I haven't had it tested but it's way easier than the usual Bulgarian microbes. Assuming the cultures are as labeled, I have to imagine eating live culture yogurt is more likely to propogate than loszenges made in a factory though.

I've made the L. reuteri "yogurt" from the BioGaia Gastrus tablets from amazon and it works well. First batch is a little watery but after that it pretty much looks like greek yogurt when I use half and half.