It wasn't the store. It was a brand. They were doing a fitting at a shop in the loop but it wasn't THEIR store. It was also several years ago, not last fall, so I would question whether or not they have survived. My suggestion would be to go about tracking down the woman mentioned, Dorothy Jones, who made and fitted the corsets.
I also believe that corsets were featured, if not THESE (although, how many can their be?) in Saint Louis Fashion Week during their section of handmade goods. That would be another avenue to try.
My guess is this is her. http://www.linkedin.com/pub/dorothy-jones/35/769/929
She's the woman with the answers.