Why don't you simply do a digital download in multiple formats (pdf, audio, and whatever other forms might sell) and sell it yourself for whatever price would work using Paypal? Market it via social media. There is a concept of BOPP (bottom of the pyramid...can't remember exactly, but read a book about it by an economist who I believe had an Indian [i.e. of India] sounding name) that says selling for miniscule amounts to the 4 billion people on the "bottom of the pyramid" is a coming trend...