The cost to incorporate in Illinois, if you're submitting your Articles of Incorporation through the mail using paper forms, is $180.00; expedited online filing is also available for corporations that have a business purpose of "any and all business purposes" that wish to have only one class of stock.
The Department of Business Services is a host for many other business and consumer resources: the enforcement complaint center, investment advisors, trademarks and service marks, and investor education services, to name a few.