That Somebody at the University of Nebraska is Quentin Faulker, who has done brilliant work on J S Bach's organ practice. I've previously recommended his Orgelbüchlein edition:
http://www.wayneleupold.com/hot-vol-2-j ... er-ed.html
at least as much for the various essays as for the music itself.
This is unfortunately rather expensive, but I think it's necessary for people who want to know what the latest research says:
http://www.wayneleupold.com/the-registr ... entin.html
Fortunately, you can average the price with this brilliant translation of the single most important treatise from the period, Adlung's Musica Mechanica Organoedi, extensively annotated. The electronic edition is free:
http://digitalcommons.unl.edu/zeabook/6/