I LITERALLY just asked this same thing! i too have to take my car in for emmissions test and my check engine light has been on for 2 months!!! obviously we have to pass in order to get new plates!
i live in Schaumburg and asked too for a decent shop to go to w/o getting ripped off - because EXACTLY what happened to you is what i want to avoid since my dh was out of work all summer and we can't afford something like that! so check out my thread - look under automotive i believe is where i posted it there is a whole list of people who recommended me to places that are good! look for my post!