Yes and no. Cob itself is cheap in cash (free really) but expensive in time, energy, calories, and sweat. It is also only the walls of whatever structure you are building. Like any other structure, cob structures require a foundation, a roof, windows, doors, appliances, etc, much of which can not be made from cob. Building with cob is a creative endeavour however, and anyone interested in giving it a try will no doubt also find joy in the hunt for the salvaged fixtures that can greatly offset the cost of building a hand made home. There are lots of examples of people who have built beautiful cob homes for very little money. Here is one.
Earthen building, sustainable living, and occasional blogging