My stock pot makes about 7 quarts (about 225 ounces). Since the chicken is already paid for and the stock seasonings are cheap or free, I make my own stock for less than $5. Even if it cost $10 to make my own stock (which is doesn't), that's still 4 cents/ounce and still cheaper. I pressure can my own stock, making it shelf-stable for up to a year. The final advantage is that you know exactly what's in your stock when you make it at home.
Here's all the chicken goop left over from my roasted chicken.
I dumped the chicken goop into my biggest stock pot, which is over a foot tall and about as wide. Clean & break up some celery stalks, 2 carrots, and wedges of an onion. Don't even bother taking the papery skin off the onion. Dump in about a tablespoon of salt, a handful of peppercorns, and a few springs of thyme. Throw in some garlic cloves if you feel like it.
I don't bother with a bouquet garni because I strain my broth at the end. If you do make a bouquet garni, grab the biggest tea ball possible and use that instead of trying to tie up a bunch of loose herbs. I swear it's easier!
Bring the water to a boil then turn it down and let it simmer for a couple of hours. If foam or scum develops on the surface, grab a slotted spoon and skim off the foam every so often. Running the spoon through a bowl of water will help get the scum off and make this task easier.
After a couple of hours, put another massive pot in the sink and put your colander in it. A friend told me a story about his mother, who had labored over a turkey stock all day only to strain it through the colander straight into the sink. To quote my brother, "I would kick my own ass if I did that".
Rinse the first pot, grab the finest strainer you own, and strain the broth again.
Now you'll have a massive pot of gorgeous, homemade, and yummilicious chicken stock. Let it cool on the counter (don't put it in the fridge hot or it'll raise the temp of your fridge and imperil your other perishables). If you want to cool it rapidly, use an ice water bath or put it in lasagna pans to increase its surface area. If you cool it down and refridgerate it overnight you can skim the hardened fat off before freezing or canning the stock.
I like these containers a lot for soups & liquids because the lid is very secure.
If you have a pressure canner/cooker, you should can your own stock. I'll show you how tomorrow.