There have been a few comments on various bargains about the cable used on WD USB 3.0 external drives.
It's not a WD proprietary cable. The drives use a standard USB 3.0 micro b connector. http://www.activemp.com/USB_drives/superspeed-usb-30-overvie… (scroll down to the bottom)
Once you know what it's called it's pretty easy to find them e.g. http://www.selbyacoustics.com.au/storefrontprofiles/DeluxeSF… (no connection with this site, just using it as an example)
I'd expect over time we'll see this connector used on other USB 3.0 devices.
my USB3.0 HDD from staples came with a very unimpressively short cable.