What alternative would you suggest?
Inject either spores or liquid culture into either hydrated rye grain or popcorn. Shake accordingly, and then mix with a substrate. And then case. And then fruit BIG. Really, I did a LONG description above. And then realize those FUCKING compact jars of slow growing myc in those PF jars are STILL not done.
That list of things above sounds like a difficult process as compared to PF, but really, I've been there, and it's WELL worth it.