They made the signs, planned how they would transport all the needed materials to the street corner, debated price vs cost, as well as marketing strategies (verdict: smile sweetly and wave). It was also decided to use walkie-talkies to communicate, as they expected more sympathy if I wasn't present.
Such a perfectly American thing to do in one's childhood, don't you think?
**Update. The girls sold out and had a net profit of $39.35. They were excited to say the least!