Here's a great example of a low-end disruptive business model: Psychotherapy for All
The more I work on the creation of disruptive business models, the more I'm convinced that there's almost always room for a disruptive model. One just needs to start with human needs and look hard, work hard for it. The design process needs constraints. A lack of viable solution spaces is more a reflection of poor innovation process than a statement of fact; it is a lack of generative contraints which leads to dead ends.
I can think of no better design constraint for the genesis of disruptive business models than trying to serve the needs of people living on a few dollars a day. What, for example, might happen to pace of innovation in our US healthcare system if we were to take notes on disruptions such as this one, or from the Aravind Eye Care System?