I didn't go there, but I have had a lot of friends go there and lived in Illinois for 7 years, and it is a decent school with solid academics at an extremely good cost (not to mention the gorgeous campus, I have visited, and it is in one of the prettiest parts of the state). As far as the admissions statistics, you are WAAAY above the averages at SIUC. They have an acceptance rate that floats at about 70% of their applicants, and their average ACT score, while it has been rising, is still only about 22 or 23. Also, 31% of their 2009 freshman class was not in the top 50% of their graduating class in high school. If these things are really that important to you, I would recommend looking into the University of Illinois, which you would stand a good chance at getting into. If you are from Illinois, the cost of attendance is still quite low (and it's not that expensive for out-of-staters, either), it is an extremely good school, and they have a med school, as well.
If I were you, though, I would get rid of the academic elitist undertones I am sensing in your post and visit the campus. Talk to some professors and students and decide if it would be the best school for you. If you absolutely love SIUC, then go! With your stats I'd be shocked if you didn't get enough scholarships to cover at least the majority of your expenses, if not all of them. Just choose the school you think is best for you based on YOU, not statistics found on a website or sheet of paper.