I made one of the DIY wonder bags. Don't waste your time or fabric. Total failure. I am a capable sewer so I am confident it wasn't me. You are correct, this is a better purchase than DIY. We will be buying a wood cookstove for our home by years end and we expect to have a large energy savings. I also made several door draft stoppers for our exterior doors. Basically, a long, round (about 3" diameter) piece of fabric stuffed with rice that lays at the bottom of your door (on the interior side) and helps to keep any draft from coming into the home. Cheap and easy to make!
RE: Simple ways to use less energy and stay comfortable!