CC in Peoria, Il. has been a little helpful for me. They contacted me several years ago when my BMother wanted to see if I would be open to communication. At the time I wasn't but since have started looking for her. They are willing to start a search (that they already have info on) for $300.00.
I finally had to send them a pretty heated letter just to get the date of my adoption, the county, and the case number.
The state of Illinois also offers a CI search program for a little under $300.00.
CI Illinois
It is free if you were in the DCFS system which is my case. Personally I would rather give the money to the state of Illinois than one of the "Charities".