So I stopped by my local game store (who's owner is friends with Ben
) and picked up a GCN and some 3rd party Xbox controller because I wanted the triggers. Well, turns out that they were better than I thought! They've got a lot of length to the whole assembly, so it's stable. Also, it's got room where the trigger hits on the end to stick a tact switch for the button on GCN. Another plus is that since it's xbox, there's R3 and L3 buttons, which means free tacts for Jidan 
Here's a link:
http://www.amazon.com/Xbox-Precision-Co ... 49&sr=1-12" onclick="window.open(this.href);return false;
Xbox Precision Controller
Pictures:
Trigger:
Controller:
There's not a ton of travel on the triggers, but enough to make me happy, and it seems similar to what the GCN has
This thing only cost me $2, too MY ONLY QUESTION: I have no idea if any kind of values for the pots on the triggers would matter in using it for GCN. I can't imagine it would matter all that much, though
Turns out that the Gamestop xbox controllers also have the same triggers (thanks joey)