With a degree in Business and minors in Economics and Political Science....I wonder what I might sub in?
The fact that you have a college degree will make you very attractive to most school systems, regardless of what it's in. Many school systems only require a high school diploma or its equivalent. You would be subjected to a criminal background check, of course, and you might have to take a short training course to orient you to classroom management, subject matter, school-wide expectations and schedules, etc. Some systems require this kind of course and some don't. Your pay won't be fantastic, but it's better than minimum wage and you're free on most days by 3 pm. IF you're willing to sub in any grade K-12, you'll be more likely to get called after your application has been accepted. (In my area, the local school board decides whether or not an application to substitute teach is accepted.)
However, I would advise you to be honest with yourself and decide what you can take and what you can't. Some people would never consider subbing in a kindergarten class while others would go no higher. With most school systems divided into elementary, middle, and high schools, there's a wide range of grades to choose from.
lefty has been doing substitute teaching. She would probably be glad to fill you in on her experiences. I think you should give it a try, PT...nothing ventured...and all that.
Also, there are many websites that you can go to for information...one of my favorites is http://teachers.net/mentors/