The islands of Bonaire, Saint Eustatius, and Saba make up Caribbean Netherlands and are part of the Netherlands. The islands have independent customs regulations. This means that anyone who imports, exports, or transits goods on one of the islands will face customs formalities, irrespective of where these goods originate from.
This also applies if you bring goods from European Netherlands to Bonaire, for example. The customs formalities apply fully to the goods transported between these islands. You can find information about customs formalities applicable to the import, export, and transit of goods here, aimed specifically at entrepreneurs.