Dynamat Extreme is VERY expesive and there is the same if not better stuff out there for much less.
By those numbers
12 Sq ft of Dynamat Extreme is 50 bucks
For 65 dollars you can get roughly 50 Sq ft of Edead V1.se which is 70 mils thick.
http://www.edesignaudio.com/forum_discount.php
62.5 Sq ft of Raammat60 sells for 89 plus shipping(ask for the forum discount). Raammat is Butyl Based and not asphalt like reg dynamat and others. Sticks very good and is very easy to work with. I've had lot's of good experience with this product.
www.raamaudio.com
There's also a new product out from
www.secondskinaudio.com Called Hazmat that is 65 mils thick with a 2 mil mylar Film. This is Butyl Rubber as opposed to Asphalt based as well. The advantage to this product is that it wieghs less than reg aluminized backed matting. To some that is very important for reducing overall weight.
http://www.secondskinaudio.com/products ... roductid=4
Pricing and more info there.