http://www.mcmaster.com/ and take a look at item #
9709T18 - Acoustical Damping $12.79 for 12 square feet.
THis stuff is exactly what dynamat is at approximately 1/10th the price.
I use this stuff extensively in my 'Tour and it sounds like a Lexus LS400 - no noise from the road just the subs and mids/tweets.
Also,
www.partsexpress.com and check out their car audio section. They sell a 24oz can of spray sound deadener for $20 that is as good as noize killer or spray dynamat or whatever.
First lay your mat down, then spray, then go over the whole thing after 4 hour drying time with a good rubberized undercoating and you should have ** ZERO ** noize.