Here is at least one source for Mutaflor - if anyone has other sources in the US, post them to allow readers some comparitive sources, this is the only one I've found so far.
Cocoon nutrition does not actually display Mutaflor on their website, due to some kind of sales territory thing (or some such reason, cannot remember exactly what they said on that), but in fact they do sell it. I called them, that's how I found out.
I ordered it from them, and it did arrive, but I have not tried actually taking the product yet. It is sitting in my fridge staring at me - any day now I'll try it!