Dynamat? it is quite expensive though! cause it is normally used for pro audio installations, to minimize panel vibrations, etc.
you could try shops dealing in trucks, etc.. sometimes trucks and vans use self-adhesive insulation under the bonnet and in the engine bay, used to minimize the noise and vibrations of the engine. there are lots of types too, like foam, or silver-foil-covered foam, etc etc..
what do you intend to do exactly? dismantle the doors and insulate them? and the hatch, and the pillars, and roof and floor etc ? eek!