I heard back from one of the FFLs and thought I would share the response. It seems that if the FFL is located in a homerule town then they are exempt from Cook County mag limits and they can transfer anything that is legal statewide in Illinois.
Just to clarify per Spats McGee's comment I am not trying to skirt or break the law. I plan on keeping the mags in the burbs with a family member that has a FOID. I just wanted to ensure I wasn't bidding on a gun with mags that was not transferable to someone that lives in Chicago.