For closed cell foam I just bought a sleeping pad from Crappy Tire. $10!

 

This one: Closed Cell Foam Sleeping Pad, 20 x 72-in Product #76-2521-8 ?

Not bad. Looks like 3/8" though and I think I'll try to go 1/4" max, more like 1/8" if I can find it...

 

Also, it's interesting to note that the Barymat 5 B-0B that Wilrep aka Acoustigard sells is 1/16" thick and 1 lb/sq ft.

 

That's the one.

 

Confirmed with Wilrep that the Barymat 5 B-0B is closer to 1/8" thick like the other MLV available.

 

I ended up buying a roll on ebay from seller auburndarter. US$120 plus $88.50 shipping to Ogdensburg, just across the border for me.

This was for 130 sq feet of 1/8" MLV. Split it with a friend, so worked out to C$120 each.

Did my 4 doors this weekend and will do the floorpan in early May (if not before). Made a significant difference - this stuff is it for soundproofing. I'll post a writeup later.