The Home Depot in Batavia has that stuff. I work there. It's 10in x 33ft or so for 19.97, the other stuff has an aluminum back and is 4in x 33ft for 14.97. I used 5 layers of the wider stuff in the trunk of my 04 civic coup and it worked great. My only sugestion is to use a heat gun to warm it up after you stick it on espeaially on the trunk lid because it doesn't stick very well in this temp. the only draw back is after my car (black) was in the sun this summer, a little started to peal off. Mainly just the corners and stuff. Not a big deal at all. If you have any questions, call The Batavia Home Depot, and ask for Dan in Hardware. I'm there tues, thurs, sat, and sun. The number is (585) 813-0144.
Ooh yeah, that duct insulator is absolute crap. Good for nothing except insulating pipes. After all, it's nothing but bubble wrap with aluminum on one side. The peel and seal we have isn't butyl rummer like Dynamat, but it works great.