I studied with them for about a year long ago, and have a close friend who is in an advanced status with them. It was one of my early introductions to overtone chanting (they call it the "Hu" chant), which I absolutely love! It is very ethereal. When done properly in a group, you hear each person's chant, PLUS this lilting sound that is not being made by any individual that appears in somewhere in the middle of the group circle. It is amazing.
My understanding is that it was developed by Paul Twitchell. He was a student/devotee of Kirpal Singh and wrote a novel (if I remember correctly it was "The Tiger's Fang".). He offered it to Kirpal as a tool to recruit followers. Kirpal disapproved of it. Thenk Paul started his own version known as Eckankar. That's what I have read as I have studied it. I can't prove or disprove it (although I have seen a picture of Paul with Kirpal).
Eckankar does charge money for each level of growth.
There is a book, "The Path of the Masters", by Julian Johnson, which details the overarching path that Eckankar is a part of. It used to be a bit hard to find, but I see it is on Amazon now. There is another book, "The Pilgrimage of James" that is a detailed story of a personal experience on this path. It is allegedly a novel, because the writer was a university professor, and did not want to tarnish his reputation. It is difficult to find.
All of these, including Eckankar, do teach some profound practices in what most would call "astral projection", or OBE's. They might be considered a bit different, though, because they go into realms that are far beyond the astral.
If you have other questions, I'll do my best to answer them.
