When travelling abroad, having a cell phone that functions abroad is a must. One can't get a multiband mobile phone for under $50, that would appeal to a teen.

I have suggestion that is certain to draw laughs here. It's a personal item and might not be appropriate for someone you don't know well. It's very useful though.

Renaissance Premium Travel Bidet / Portable Bidet

A neck wallet, or a wallet one can wear under a tee-shirt to keep one's valuables. His parents probably already thought of that.
If I were to do it today and did not feel comfortable with my suggestion, I would go with cash.
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