Hey hold on a sec! You might want to reconsider this -even cancel the event, at least until you obtain a Part 107.
I totally forgot an important interpretation of the "furtherance of a business" by compensation in regard to this seemingly innocent display of a hobby. And I'm not talkin'bout the peanut butter & bribe sandwich from a kid. I'm surprised that none of the other contributors caught it, especially
@PatR and
@Phaedrus who we have all come to count on to remind us of the finer details and nuances of the FCC rules and regulations. And quite frankly I am even more surprised that the local FSDO didn't catch it either. There is in fact a business that will potentially be furthered by this.
...The Retail Drone business!?