If you are working with a Realtor, she can access the information for you if the sale was an MLS sale.
Otherwise, you can go to the Cook County Recorder of Deeds website and see the Deed info, which includes the purchase price and grantor/grantees, online: http://www.ccrd.info/CCRD/controller
If you don't have the PIN number, go here first to search for the PIN by address: http://www.cookcountyassessor.com/filings/searchflat//search.asp
When you work with a real estate agent, they can pull up the sales history of the house, in most cases. We pull this information, current area information as well as what is currently on the market and recently sold houses similar to the one our buyer may be interested in, in order to help determine an offer price.
We hope this helps! If you need any additional help, please let us know. Feel free to visit our website and register if you would like to view the entire MLS of Northern Illinois.
Frank and Lorena