Answer: That is a tough question to answer because there are so many types and thicknesses of insulation. Owens Corning makes both fiberglass and foam insulations, for example, while some products have a facing on the surface and others do not. The insulation for attics is thicker than the insulation for walls, because walls have a limited amount of space for insulation and the top of a home's living space is the most important to have well insulated. Further complicating the matter is the fact that retail prices are set by the stores that sell the products to contractors and consumers. If you are looking to upgrade the insulation in your home's attic, you should be able to get the product you need for a few hundred dollars. If you are building a new home and want it to be well insulated, you should expect to pay a few thousand dollars.