I went to Columbus last Friday for the Running of the Brides at Filene's Basementwith my future sister-in-law. We were all a bit weary about going and whether or not we would have success. We did not go at 8am with the crowd, but showed up around 9:30-10. There were plenty of dresses in various sizes to choose from. Obviously, the majority of the dresses were sample sizes 8-12, but there were sizes both bigger and smaller. My FSIL found her dress for $250. It is a James Clifford, which is a couture designer that retails usually upwards of $2,000 (my dress was the same designer, but we paid full price).
I would say that it is definitely worth a shot if any of you are considering it. There is another one slated for August in Cleveland.