I'd be curious as to why you're looking in Illinois. If I didn't live here I wouldn't invest here. We have net population outflow in most markets and the tax situation is likely to go from bad to worse over the next 5-10 years. Just curious what your market analysis indicates as the short, medium, and long term prospects driving you to Illinois. I'll add some links below for articles on the net outflows for the state - should help in targeting those areas (like Champaign as Anna mentioned) that are at least population stable in stead of shrinking. Another note - I would avoid Champaign for now. We're putting on waaaay too many multifamily units these days and I think that's going to compress rents for the next few years and ultimately make the market less attractive.
Links here and here for some interesting info on population.