Finding a van in Chicago that's 20+ years old, rust free, and most important, roadworthy is going to be a very difficult task. Finding one under 100,000 miles might make it impossible. You're looking for a very specific, and rare, vehicle, and while you might be able to find one, you are setting yourself up for a bit of a needle in a haystack.

If you do find one, I'd grab it quickly - after taking it to a mechanic for a full inspection. Keep in mind, if you're registering it in Chicago, it probably also needs to pass an emissions test. I also question how easy it will be to title and register a car in Illinois, without an Illinois Drivers License, but I do know that IL does require you to have insurance to register the car, so make sure you also have that lined up in advance.