SilverGlo costs $.35 a board foot compared to $1.50 for a 200 board foot kit, $.1.05 for a 600 board foot kit or $.88 for refillable foam. So let's say you laid 2" SilverGlo on top of the trunk ducts radiant barrier up, and then spayed the sides and bottom of the ducts. You'd save about $1.20 for each square foot of SilverGlo you install!