This is too easy to make. Take any leftover chicken you have (skin, bones, grease, little bits that did get eaten), put in a crockpot, fill to within 1" of top of pot and set on high overnight. In the morning, take the pot out of the cooker, allow to cool, refrigerate until the fat hardens, skim it off, then package in 1 cup increments in the freezer. Or, fill ice cube trays with the stuff, and pop out the cubes and put them together in a bag - you'll have about 1 ounce of broth per cube. This uses up pretty much any value left in your leftover chicken carcass in a productive, cost saving way. PLus you know what in it!
That's the basic, here's the specifics
*If you only have a few little bones and skin (not a whole chicken), either use a smaller crockpot or only fill half full of water otherwise your broth will taste watered down
*You can add onion, celery, carrot, herbs, whatever you want for taste, I personally like it plain
*If visible bits of sediment in your broth bothers you, run it through a coffee filter over a clean pot, that should take care of any bits and give you a clearer broth - but do this while it's hot because the broth tends to thicken when cold
*If you've never done this before, it's an easy and almost free way to experiment - the crockpot does not use much electricity, it's only a few cups of water and you were going to have to toss the chicken carcass or bones anyway.
*Putting the chicken grease from your initial cooking in the pot is only for the purpose of flavor infusion. when you refrigerate the cooled broth, it will harden at the top and you'll easily be able to remove it for a virtually fat free broth.
*Swanson is about 1.50 a can and still contains some ingredients that I don't know what they are.