International Film Buying Day Update

I'm quite surprised by the popularity of my idea (see somewhere below for more details or click on the title above). So far the Flickr group has almost 150 members and most of the feedback has been positive. I wonder if the growth of the group will accelerate, how many people do we need and how many rolls do they need to buy to really make an impact? I'm trying to find some sort of sales figures for film but none seem to be readily available or I'm just not searching for the right thing. If for instance we could find out that 10,000 rolls of film are sold on average every day. If we can get 20,000 participants we know that on average each person must buy 5 rolls of film to make a significant difference in sales for that day. Maybe if it looks like we can't make an overall impact, we could just single out retailers in particular towns or on-line and see if we can cause them to sell out on that particular day.