Are you certain you are not confusing U of I with Northwestern? U of M's out-of-state tuition is approximately $33,000, and I am dubious that Illinois' in-state tuition is comparable to U of M's out-of-state tuition.
Allright it is at 30k but by the time I enroll in fall 2010 it will be at or around 33k. I know it is much higher compared to other big ten public schools, but that's what I get for living in a state with a uber liberal government.
For Northwestern University it is about 45-50k a year.