We think the microbes that make biogas from food and/or toilet wastes are truly special but the fact is they are ubiquitous. They are found everywhere! You can source them from almost any animal manure (including your own 'humanure' -- we started systems on our baby's diaper wastes) and even from most lake and pund muds (we started a system on some sediment Culhane brought back from Mount Everest Base Camp!). So don't be fooled by anyone telling you you need to buy special cultures. You CAN use septic assist products (we've used RidX, for example, as it has cellulase, lipase, protease and amylase in addition to live microbes), but that is your call. We generally get ours by going to a stable and collecting horse manure. We've followed cows and pigs around their paddocks and we've even spent time in Botswana scurrying behind herds of elephants. Everything worked great except the elephant poo in Botswana. We aren't sure why. But people have started systems on dog poo, cat litter and alpaca poo. Give it a try. Just remember -- you want a CONSORTIUM of microbes, not a single species. So this isn't like making beer or yoghurt exactly. It is an ecology you are creating!
Are there commercial preparations or do I have to do it myself?