File your appearance anyway and ask for time to pay the filing fee. If you don't file your appearance, default judgment will be entered against you. If this is a small claim, appearance fees are often no required.
If this is a debt you owe and the amount of the debt is correct you may not gain much if anything by filing a response. If your overall financial situation is dire you may want to sit down with a bankruptcy attorney to explore that option.
After consulting with an Attorney as to whether you should defend on the case, you can go to Cook County Circuit Court Website and click "Court Forms" on the left side, then click on the search tab and enter "APPLICATION AND AFFIDAVIT TO SUE OR DEFEND AS AN INDIGENT PERSON", it will bring up CCG N689A and B, which you or you with your attorney can fill out and take to the Court Clerk, who will then direct you to a Judge to hear, and usually grant, the request, thus allowing you to participate without paying the appearance fee.
All postings are first impression opinions only, and are not intended to be taken as legal advice or to be acted upon without review of the underlying facts and further refining of such opinions to account for these facts. No attorney client relationship is created by this posting, and these communications are not privileged and are part of the public domain.