It has 5 connectors. Red, green, & blue for video, plus red & white for audio, as pictured:
(image from nintendo.com)
To check if it's an official cable, see if the Nintendo name and model # are stamped into the console plug.
I'm aware that it can be ordered from nintendo.com, but the price to Canadians is $35.99 (compared to $29.95 for Americans). I've checked eBay as well, but the pickings (especially those that will ship to Canada) have been slim lately...
For a cable in good cosmetic and working condition, I'll pay $26.05 CAD, shipping included.
EDIT: Found one on eBay for just 40 cents above what I was asking.
Edited by TurboChickenMan, 14 November 2012 - 04:51 PM.