Birch71, why would an fx prop firm be of interest to you? Is it training / mentoring you seek, or something else?
http://chicago.craigslist.org/chc/acc/211740247.html Is this what you're looking for? Plenty of prop in Chicago, but mainly futs and stocks.
There are many FX props in Chicago. And no, I'm not just talking about my firm. I bet there are at least 20.
Who else is there? I only know of these: Gelber Goldengerg-Heymayer Tradelink Fxchi.com And, it sounds like most are basis traders. Do you trade at a FX prop firm?