I purchased dynamat, but then found that second skin pro was a superior product. I ended up purchasing some more because I still had empty spots
you're just going to do the rear section (hatchback coupe) about 45-50 sq feet will do fine.
Best price i found for dynamat extreme was $300 for 72 sq ft
Second skin's damplifier pro (better product) is $280 for 80 sq feet.
It is possible to do the cargo area, rear wall, doors, wall behind the seats and most of the floors with the 80 sq ft shop pack.
I'd also look into the overkill absorption foam espcially if you have a loud exhaust. I used it all over the cargo area and it significantly reduced the noise of my borla stingers.