You can buy a kefir drink from the health foods store rather than going thru the trouble of making your own from grains - that IS a hassle!!! :) Even a store-bought drink has tons more cultures than yoghurt.
Any acidophilus/bifidus mixture in the refrigerated section are live cultures. That's why they're refrigerated. Sometimes they're called "yoghurt starters." I like Spectrum's brand of supplements, I think they do both probiotics and EFA oils.