The Belkin Audio Splitter is exclusive to Apple Stores got it for me when she was there. It is retailing for HK$148 (S$24).
It is a very simple no frills 3.5 mm (1/8 in.) audio jack splitter and definitely way overpriced. If you are using headphones/earphones with a microphone, the microphone part of it will not work because the splitter doesn’t transmit it to the phone.
When I first looked at the packaging, I was expecting it to be stiff but surprisingly, there is a some flexibility in it.