We are making our own dehydrated meals with mylar bags and oxygen absorbers. This is very cost effective, but less so if you need to spend lots of money for one of the specialty tools for sealing these bags. What cost effective alternatives are there to buying a sealer just for this purpose?
It looks like what you need is something hot enough to melt the sides of the Mylar bag together to seal it. Two DIY options are a clothing iron or a hair straightening iron.
If using the clothing iron, a flat reflective metal surface underneath would probably help. In either case it would probably take some experimentation to get the settings just right. For more information I would suggest these two links.