There is no cost associated with visiting "Saint Zandvoort Castle" as it does not exist. Costs in Zandvoort depend on the actual attractions visited.
As "Saint Zandvoort Castle" is not a recognized attraction, there is no admission fee or associated cost. If you are inquiring about general costs when visiting Zandvoort, these would pertain to its actual attractions and services.
For instance, access to Zandvoort beach is free. However, parking in Zandvoort is typically paid, and costs for beach chair rentals, food, drinks, and watersports activities will apply. Entry to events or tours at Circuit Zandvoort involves ticket purchases, with prices varying greatly depending on the event. Exploring parts of the national park is free, though bicycle rentals might incur a fee. Overall, your budget for a visit to Zandvoort would depend entirely on the activities you choose to pursue.