Housing prices are reasonable and rents generally are as well. But that all depends on where you choose to rent. If you are close to the University, you will pay more for less simply because the landlords know that they can get away with it. Once you are out of easy walking distance, the rental rates drops sharply. You may or may not be subject to a credit check, but it never hurts to have a few references handy and be prepared to pay the security deposit on the spot.
University: This neighborhood encompasses everything within a 1 mile radius of Morris Library, more or less the center of the SIU Campus.
North Giant City: This is the area with a lot of cheaper houses.
City Center and Country Club: Homes are worth more but the average is still pretty low by most standards; you can get a McMansion for _significantly _less than the national average. Rental prices are lower here than the university area because there isn't as much demand.