Family Reunion Fairness?

My (rich) cousins want to have a family reunion next year. They are almost dead set on having it at one particular place. This place includes food and drinks, tubing, kayaking and wading, miniature golf, gazing zoo, rock wall, moon bounce, ping pong, train ride, 1 kiddie ride and a giant slide. They are charging $35 pp ages 6 and up and $25 pp ages 2-6. It will cost me $190.00 for a 6 hour reunion at a crowded place and my kids won't even be able to do half the activities and they certainly won't eat $25 or $35 worth of food. However, if we have the reunion at a state park, they can fish, bike, hike, play organized sports, play on a nice size playground, pet horses, or go horsebackriding (extra fee). We could do a pot luck and have our own covered picnic pavilions, kids games, and NO CROWDS. A pavilion is only $35.00 and making a dish for a pot luck and buying soda is inexpensive. Should I tell them my idea? Should I bring up the cost to them? I love my cousins, BUT...........