Voluntary Simplicity, has been around for 25 years, the first edition having been published in 1981. The author, Duane Elgin, describes himself as a former senior social scientist connected with an institution in California, and his biography mentions a business degree and an MA in economic history. He seems to presently support himself as a writer and motivational speaker. There is a political or moral dimension to his work, but his metier is self-improvement and spirituality. For a sample of his recent writing, there is an article at a site called Soulful Living.
I read a copy of the 1993 edition of Voluntary Simplicity which incorporates the findings of his simplicity survey, and has an Introduction by Ram Dass, the former Richard Alpert.

A couple of the chapters are fairly good, posing important questions about possessions, materialism and consumerism. People tend to let themselves be pushed into buying things we don’t need because everyone else seems to have them and want them. He says, quite rightly, that we should savour what we have. Another chapter is devoted to the idea of living intentionally.
These ideas aren’t new, of course, although they don’t seem to occur to many people. The book is useful as a starting point for thinking about the issues. It’s still very basic, and it falls down. It’s not homespun, colorful or authentic, and it’s not as deep or precise as books informed by the ongoing discourse of professional philosophers. Back in the 70’s, Elgin chose to live in an alternative situation in the counterculture, on the fringes of the American dream. The first edition of the book was a justification of his choices. His career evolved and he became a free-lance guru. The second edition presents the same justifications of his preferences, now supported by quotes from a mixture of credible-sounding sources and a so-called survey that seems to be a collection of fan mail for the first edition.
There is no clear, specific, economic advice on how to live simply, and a minimal explanation of the concept of living intentionally. He oversimplifies the problem of consumerism. People don’t just buy things because we are greedy or stupid – we make choices based on cost, convenience and social custom. He demeans people who live ordinary lives. He implies they are not authentic, highly evolved spiritual beings. This becomes clear when he starts to teach his own ideas about living spiritually.
His plan involves detachment from material things and self-referral (trying to split off part of your mind and trying to watch yourself acting and listen to yourself thinking). His basic rhetoric is the right moral life is a simple natural life lived honestly and authentically. What he really means by this is living close to nature, limited use of technology, heavy focus on spiritual practices, dismissing much of what is valued by most people in society. The book mixes enviromentalism, anti-corporate politics, popular psychology, American transcendalist literature (Emerson, Thoreau, Whitman) and pseudo-Hindu mysticism. It’s personal insight posing as learned discourse, a badly written, poorly reasoned prophecy of a coming New Age of enlightenment and peace.
There is a sort of false pretence running through this book. He starts out posing as a reasonable person, with practical advice but he is really pushing a more spiritual or religious program. He seems to think that he is a superior, compassionate, highly-evolved being. This all sounds basically condescending and it’s hard to listen to the bullshit.
There is a wacky emotional streak in American religion. Conservative Americans tend to go for the emotional intensity of pentecostal, charismatic and fundamentalist worship. More liberally inclined Americans tend to go for theories decorated by positive thinking, bad poetry, lousy music, Eastern religion and drugs. Both positions involve some degree of disengagement from the hardships and injustices of the economy and the world political order, both groups tend to judge and condescend to people who don’t talk their language. Both groups tend to control intrusions on their beliefs by a mixture of methods. Where possible, they use political action and law to shape the world around their beliefs, but they often withdraw into their churches, sects and cults to talk to people who share their values.