I don't know if you'll find one locally (definitely not available at Katranji nor Radioshack), but if you're willing to orderone on-line, this one from Kanex comes highly recommended:
I know this is an old thread, and may Nabs rest in peace, I know he was such a helpful guy...
Does anyone know a place where I can buy this MHL HDMI micro USB cable for my Nexus 4?!
The screen is completely black/dead and I wanna try to log into it by this method.