Just an FYI for you folks in the Austin area. I found a source for 109" wide aluminum on rolls cut to length here:
http://www.jfstrucks.com/
Price was $26 and some change per foot. Don't know how that compares with what others are seeing. He also carries 4x10 sheets with covering on both sides(paint?). Didn't get price on that.
ed.: He also has trim (he called it j-trim) but I don't know what exactly it is. When I get aluminum I'll let you know.