Reef-safe and Hawaii-safe sunscreens do cost a bit more than a mass-produced chemical sunscreen but it's not drastically more expensive. And the shared human cost of destroying coral reefs will be far greater. Expect to pay around $12-$15 for a tube of reef-safe sunscreen, though, of course, the coast varies greatly based on where you are. It’ll cost a lot more to buy it at a hotel gift shop in Hawaii than it will if you buy it online in advance.