My 2 cents (and prob doesn't apply as much to MBA or Law School programs):
1. I'd go see a graduate advisor and talk to them. They should be very blunt about your chances and let you know what you need to do. I did this at UT and was literally laughed out of the advisor's office but that's what happens when you have a C undergraduate average in Liberal Arts.
2. One thing that most people don't know is that you can still take UT undergrad classes after you graduate. If you are serious and think you need some extra help, re-enroll to UT and sign up for a graduate class as an undergrad in the department will be applying. You will need to go the professor and ask their permission, but as long as you are taking it for a grade and not auditing or pass/fail, they prob won't have a problem with it. This will get you used to school again and if you make an A (in grad school anything below a B is bad), you can use the professor for a referral on your graduate application. This will show that you are serious and can handle grad level work. I did this and although I made a B, the professor wrote me an appropriate referral and that was the only reason I was able to get into my grad school. If you are not in Austin, doing this may be difficult but if you can take a grad class near you, the same applies.
3. Figure out what you want to focus on. Grad work is typically very specialized and coming into the application process with a good idea of what you want to focus on will be very important. The more precise, the better.
4. A cursory glance shows that UT has a terminal masters program for Economics. If this is what you want to study, I personally think your grades would be fine (the advisor would be able to confirm). If you want to get a PhD though, I would guess you might have to show do a bit more to get accepted. Doing well in a grad school class or two might help but you may even have to get a grad degree elsewhere before applying to the PhD program. They may allow people to transfer into the PhD program after they have finished the Masters but since it is labeled as terminal, I have the impression this may be difficult.
Again - these are just my opinions, I am sure others have their own first hand experiences and may offer different insights.
Good luck - I really enjoyed grad school. It was much more difficult than undergrad but I was more mature and studied subjects I was way more interested in.