So I was meandering through Big Lots today looking at their stuff. I just happened to noticed a couple of rolls of flooring underlayment. It was super light weight (I don't think the whole roll weighed more than a pound and a half) and appeared to a be a 1/8" CCF type material. For the price ($20) there is more than enough material to make two 4 layer underquilts. Has anyone tried to use underlayment for insulation in an underquilt? The price and weight of this makes it incredibly tempting. Any thoughts or suggestions would be greatly appreciated.