If you are pulled over at customs, you might struggle to justify why you need so many mp3 players and phones. If they are brand new and boxed it will also be a give away. I do take a fair amount of elctronic equipment with me and have taken some surplus laptops, phones ...etc over for my g/f but it has all been my own equipment which is no longer required.
Incidentally, I do sometimes carry in my hand baggage or case, 2 laptops, 2 phones, 2 or 3 cameras and camera equipment, a HDD and countless flash drives. All of this is for personal or work use and I could prove it if I was asked to.
