Tight budget? No problem: Do a Target or Costco run when you arrive: buy snacks/drinks that you continuously stock on a cart for people to grab from.
Best lunch bets: box lunches are often affordable and allow for mobility in sitting outside or in one’s room if a mental break or working lunch is needed. This is great for a single-day event. For multi-day events, offer variety in your lunch offering, choosing a hot meal one day, a boxed lunch another.