One of the problems with that is that it’s usually quite expensive. Most of the time, I get around the cost by using the far more economical option of bouillon cubes and water, but sometimes I just use the cheapest option of all - water and salt.
Because the truth is that salt is the major component of canned broth and bouillon cubes alike, with only minimal other ingredients. The sodium content is typically quite high, particularly in the canned versions, with only somewhat less in the bouillon cubes.
One way I work around this and you can, too, is to dilute the broth with extra water.
Real broth - or stock, as it’s also called - is of course made by simmering vegetables and/or some kind of meat for an hour or more on the stove. I use it in almost all of my soup recipes, so I am very familiar with the process.
But until I had the opportunity to spend the day in a professional kitchen during a visit with some of my students, I had never heard of this “poor man’s” approach to making stock.