Tiffany is going to the beach and wants to make sure she has enough sunscreen. She knows she needs to re-apply sunscreen after 2 hours. She also knows she needs 3 ounces of sunscreen each application and a bottle contain 12 ounces and costs $3.5. If she is there for 16 hours, how much will the sunscreen cost?
Please reason step by step, and put your final answer within \boxed{}.
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