Congratulations. I don't know if SLU is $30K better than Mizzou, as Mizzou's program is also ranked and well regarded. In the end, there are only two things you really need:
1. For a program to prepare you for a professional opportunity, and...
2. A firm belief that a program's internship, faculty and alumni network will give you that opportunity.
Both these programs meet these requirements.
Cost notwithstanding, the locales might also be a factor for you. Columbia is the quintessential college town and Mizzou has a great football program and a gorgeous campus, so if you're into that sort of thing...
St. Louis is a city and thus has everything that comes with a city: pro sports teams, museums, traffic... There's some overlap between the two schools but also some significant differences. Have fun deciding, I don't think you can lose with either one...