From the Antigravity DYI pot cozi list:
(1) 8″ x 25.75″ piece of Reflectix® for the perimeter of your cozy
(2) 8″ x 8″ pieces of Reflectix® for the top and bottom of your cozy = $11.95
Menards you get 25 sq ft for $11.39

I made my own cozy out of Reflectix that I could slide a 1-2 qt pot into. If you want to do the individual food pouch route I still think putting pouch in small pot then cozy is better than those stand alone pouches which I bought and now regret I did.
IF there is a difference in the two Reflectix you'd need a micro-meter to tell.
Problem is you need to keep pouch upright or you end up with mess. I found the pouch in pot a cleaner way to go.
I also went a little further on the insulation side.
Once the pot is in the cozy, I set it on a piece of Thermarest pad I use around camp, fold over and put a rock on each end, sort of a pouch within a envelope.
Leave in about 20 minutes and your meal is piping hot. I only stir it once really well when I add the hot water and once again before I eat it.
Saves a lot of fuel not running your stove even on low simmer.