For fundraising and charity scent dinners, the organization covers my fee and travel expenses and establishes the date of the dinner and the restaurant.
If the restaurant does not donate its services, it will establish its per-person fee, say $100/person. If the organization charges $500/person-- benefit prices have ranged from $200 to $3,000 per seat--and invites 100 guests, 100 guests x $500 = $50,000.
Depending on the organization I may lower my fee or waive it altogether.