There is still a shuttle service called Coach USA / Wisconsin.
This web link should give you some information.
http://www.flychicago.com/ohare/groundtr��
There are also some limo services that will go between the two airports, obviously a bit more expensive.
There is also public bus transportation, but I would not suggest it - especially since you have a small child with you.
Good luck
Taxi will cost about $45, give or take, and you should be there in about 30-40 minutes (unless you_re traveling during rush hour and then plan for a good hour). They do charge an additional $1 per person. I wonder if they would actually charge for a 2 year old?
As for time planning, it takes 45 minutes with no traffic, and about an hour to an hour and a half if it_s rush hour, between 4-6pm.
Best of luck :)
There is a bus that travels between the two airports $14 per person.
If you have more time you could try the cta ($2.5 per person). Take the blue line and transfer to the orange line at clark/lake. For this route, I would schedule 2 hrs of travel time. Not the fastest, but cheap.
http://stretchlimochicago.com/
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The trip will cost you around $60 in black town car plus you order a car seat rental too for around $5 extra.
http://www.coachusa.com/wisconsincoach/s��
Check the following link to a bus line that runs between them