Answer 1: Of course he can get a 3DS for 50$, because companies just LOVE to sell their stuff at a loss.
Answer 2: Yes, he can get a 3DS for 50$. After he paid 200-250$ before the 50$.
Answer 3: Yes of course. It will not be from Nintendo, though. His 3D-S will be a high quality system made by the great Chinese company Nintondo.
edit: I'm quite sure only one of the above 3 answers is correct or almost correct...
Need something off Play-Asia? http://www.play-asia.com/