[AgentKooper]

I agree that an expensive gift from a teacher to a student has at least the potential to be problematic.

But why does it have to be a gift at all? Buy the Yamaha for your classroom and establish a process whereby any student can check it out and take it home for the night with permission from their parents (or just do that with the beater Seagull). The student you wrote about may be the only one who even wants to play it, and then there's no problem. And if you end up encouraging some other young players, all the better.