Not sure if anyone is doing any interior panel work, but I found a site that has a pretty wide selection of different types, seems to be reasonable prices as well. Aside from tar-based dynamat against the metal, I plan on using a combo of vacuum sealed insulation on the larger, square panels and some variety of thicker type for better R-value and vapor barrier where the space requires cutting in the pieces.
http://www.soundproofcow.com/
Found a nice source for sound and insulation products
Found a nice source for sound and insulation products
Where science and technology fail, art survives.