SWIM has noticed that if you have grain-to-grain transfers down pat, you can take a fully colonized quart jar of rye grain and extract with something acidic (juices, HCl water, whatever, even ethanol if you dare to heat it and destroy the psilocin) and get a pretty decent tield of shroom cocktail out of it. 4 quart jars extracted makes about 2 liters where a dose is anywhere from 100mls on up. and like i said, grain-to-grain transfers can expand a single culture or spore germination to 1000 quarts of spawn in three transfers, according to stamets. thats without even using a flow hood.
there was soneone on the forest floor a while back who was talking about liquid culture in just the fashion you're taling about too, theres a patent on a particular culture media blend. mine that site for further details.