Originally Posted by Camel

An inexpensive alternative to buying a bag, is to make one out of Reflectix insulation. Large rolls are available at most big box home goods stores, and probably local hardware stores as well.

I'd guesstimate a large roll costs 10$, a roll of aluminum tape 4$. You probably have scissors about. The left over insulation can be used about your house for its intended purpose. It's super handy, especially in colder climates, for adding simple insultaion to things like garage doors&such.