DSF

If it their event name that you are profitting from, then surely it is only fair/right that they deserve a cut of your profits - I would be looking down the route of doing a deal where you print official merchandise, and so get to use their branding/logo/name etc, and then it's either a profit share, or they buy the goods from you wholesale and they sell themselves.
Either way, best to approach them from this kind of angle, and pitch it as a way that they can monetise their event more.