The tri-state is by FAR the best way to go. Otherwise you're looking at taking smaller stoplighted streets going South a far way, or you're taking the interstate into Chicago downtown and heading South from there.
Entering at O'Hare, you'll have tolls at 1)Irving Park 2)Cermak 3)82nd and then at )I57.
Tolls will be $1.50 each. If you lived here you'd have an electronic toll collector which means you'd pay half that rate.
So six bucks each way.
The first toll at Irving park has an oaisis, which is like a rest stop on an overpass. Mickey D's, Starbucks, Fuel- stuff like that. There's another one down near I294 and I55 interchange.
I have heard peple suggest using a rental company, but where do you think the money goes? Sure you don't pay the toll directly, instead you pay rental companies.
They will charge you the full cash rate plus service fee.
For example, the Hertz service fee is $4.95 per day if you use your iPass even once. That's $4.95 for each and every day of your rental, even days you do not use the iPass, up to $25.75 per month, plus tax.