I'm no longer in Chicago. I moved back to my hometown, in Soutnern IL on the 31st.
To my knowledge, there are no stores in the Chicago area that sell sub-adult to adult Banded Cats. I raised one of mine from an egg (she was female) and the other, I picked up as an 18" male from a lady in Wisconsin.
If you go to the Wild Reef exhibit, at Shedd Aquarium, my pair are in the chest high tide pool tank. They just recently (within the past 3 - 4 months) added another female and my male is mating with both females.
I do know that Scotts Pet Store, in Westchester, sells different species of shark, that are past egg stage, but no Banded Cats.