A great companion piece to this is Comic Book Confidential (1988)

Comic Book Confidential (1988)
http://www.imdb.com/title/tt0094897/
This documentary covers the underground and independent authors from the guys who made first horror comics to underground classics like Crumb.
It's great to see interviews with all these people (like Crumb and even some well knowns like Will Eisner and young Frank Miller) and to see what was happening behind the mainstream comic scene.