Samantha is organizing a charity run. For every 5 participants, she needs 2 volunteers to help. She already has 12 volunteers. If 60 participants have signed up for the run, how many more volunteers does Samantha need? Additionally, if each volunteer gets a t-shirt that costs $8, how much will Samantha spend on t-shirts for all the volunteers? Let's think step by step and output the final answer within \boxed{}.
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