Since summer of 2014 several startup companies around the world are beginning to offer home biogas systems for sale. This of course has been the case for a decade or more in China and India, but the rest of the world is starting to catch up. If you are in Kenya check out Flexi-biogas systems from Simply Logic. If you are in the Middle East check out the Teva Gas system from Eco-gas Israel and the modified ARTI systems from "the Biogas People" in Cairo. Green Elephant/Green Box in Pune India will have a home system soon that may be available internationally and in South Africa there is the "Little Green Monster". In the United States of America we are working with Hestia Home Biogas out of Eugene Oregon and Seattle Washington whose unique rotomolded 2 cubic meter systems are now on the market and sold on the West and East Coasts with distribution out of Brooklyn.
Most 2 cubic meter systems that are made of rotomolded plastic cost in the range of $1500 to $3000 and produce enough gas to cook for between 2 and 4 hours a day. The Flexi systems from Kenya, made from UV stabilized flexible bags, are the least expensive, about $500 for the kit.
If you want to build one yourself, check out our education section. It's rather simple really! Just do it!