Oh, and sorry for the double post, but YES. You can get Illinois In-state tuition if you are an undocumented if you sign an affidavit. When I first went to college at UIC, that's what I did.
You might have to actually go to the admissions office and tell them about your situation face to face, but you will get it. The affidavits are usually available online on a college's website. Sign it and get it notarized. In my case, I couldn't get mine notarized at first since I didn't have a government issued ID. However, I picked up the phone, called admissions, explained my situation and they directed me to UIC's private notary who didn't expect me to have the ID.
So YES. There is a way. You'll have to go out on a limb, but it's all completely legal.
I'm a college senior. Yes, I did put my immigration status in my application. I wrote about in my essay. I had excellent grades, and took AP classes in High School. I was accepted in several colleges. The private college that I'm attending accepted me as International Student with a full scholarship for the four undergraduate years!