[basementjack]

2 things:

1) rigid insulation is typically available from a few types of places...
- furnace supply shops sell it - it's used to make ductwork in some cases...
- insulation supply shops sell it - look in the yello pages for insulation supply or insulation distributor.

2) don't get hung up on which exact panel to purchase and use. while there are some differences, they should be taken with perspective
- if you want guaranteed, documented performance, buy a GIK panel or a realtrap -both of those companies have done thier homework... yet even with both of those companies fine product - both will openly tell you - it takes ALOT of panels to make a room perfect.
- so take that into consideration - it's not like you if you research and find the perfect 703, that one panel will fix your problems - You'll do far better off with multiple panels of just about anything - if the specs are furnished try for something close to 6 pound per cubic foot, but if it's 3lb/ft don't sweat it.
and buy as thick as you can tolerate, and lastly, plan for them to be away from the walls - even if it's only a little bit - some of the biggest bang for your buck is a piece put diagonally in the corners.

Hope that helps - and please have a look at the site sponsors (GIK acoustics is one of them- and they practically give those panels away!)

- Jack