Of more importance than the financing of this situation is the reality of trying to run a business in a condo. Most condo associations have rules governing the use of individual units. Unless a condo is specifically zoned for business, I can't imagine most associations allowing you to run a child care business.
I know there are some websites that advertise properties that you can rent to own, but I do not know what their domain names are and in most cases they are fsbo (for sale by owner), so it would only show you a limited amount anyway. Most properties that are for sale would be listed on the MLS and I would be happy to set you up with an automated search for exactly what you are looking for. Please contact me at firstname.lastname@example.org and we can discuss this further.
In the mean time if you would like to search for some properties on your own you can go here, http://www.chicagolandrealestatelistings.net