You might think of doing a search of the Federation of Fly Fishers for a certified instructor in Illinois and see if there is one near you. Most of the ones I've met have been friendly, accomodating and knowledgeable.
They will most likely know of any fly fishing clubs in the area as well.
Find A Certified Instructor
If you scroll down on the above page, you will get to a map and can find all the certified instructors in Illinois.
I've never been to an Orvis school, but since they are expanding, I assume they are popular.