There are no third party component cables for the Game Cube. It simply never happened.
The 'cube was designed so that the Analog to Digital converter chip was actually *in* the cable. It cut costs for the 'cube and increased costs for the cable (which is why it was so expensive to buy in the first place and why no retailers wanted to carry it).
I never knew GameStop would ship stuff from store to store upon request.
Using the method of checking their online site for store pick up, back in the day, I managed to get 4 of my 5 sets of cables this way. However, as has been suggested here, it wasn't uncommon to find the wrong thing labeled as GCN Component Cables. You'd find composite cables or the third-party three-in-one cables that were component/composite for the XBox, PS2 and GCN (but the component wouldn't work on the GCN). I never found the Wii cables labeled that way, but the Wii was still new at the time.
This is the web page I'd use to locate them:
http://www.gamestop.com/accessories/gamecube-n64-component-cable-used/32149Anytime I was driving anywhere in particular, I'd pull up stores along my path and check to see if they had any in stock.
