joe, afaik people have had great success using EEG in conjunction with meditation to enter into deeper states, or even just for general relaxing. It makes sense that constant feedback would help you learn to change the states more quickly. Making tones that correlate with certain brainwave patterns is an awesome idea and would be much more conducive to meditation than watching the visual data.

Dr. Les Fehmi is one of the pioneers of biofeedback research and found that by using such techniques

he became far more relaxed, at ease, and centered. He says that his severe long term arthritis in his hands disappeared and his vision and sense of smell were enhanced. He became firmly convinced that this was the way life was meant to be. ^_^

I'm not sure how to go about getting a cheap EEG setup for this but i did see this kickstarter project blow past its funding goal, and it seems like you could use this device for this purpose. It says at the bottom in the FAQ that it gives raw access to EEG data. Not sure expensive it is though, it was a while ago that i briefly looked into it.

[URL unfurl="true"]http://www.kickstarter.com/projects/tanttle/emotiv-insight-optimize-your-brain-fitness-and-per[/URL]