The OP kinda also leaves out one thing -- Nintendo has tremendous leverage with part suppliers.
If they feel like part supplier is charging too much for a part, they can probably go elsewhere or more likely they can put heat on that part supplier.
Every part supplier would love to be in business with Nintendo given the massive volumes they sell at, I don't think any company is in a rush to piss them off. Nintendo in the past has been known to strong arm suppliers, especially when they are in a position of power. I don't think any company wants to anger Nintendo and risk a potential contract for Wii 2 and/or DS2.
Beyond that I believe pretty much that the Wii wasn't even supposed to be $250 in the first place. I believe it was designed to be $199.99 from launch, but then Sony made the huge blunder of $500/$600 launch, and Nintendo figured they could get away with charging the extra $50. The rest of course is history.
You also have to wonder about the profit margin on the Wiimote + nunchaku ... they must be racking it in from that too. Wouldn't surprise me at all if a nunchaku costs Nintendo like $1-$2 to make. After the mass production of the Wiimote too ... they probably are making a handsome profit at $40 extra per pop. Ditto for that Balance Board that comes with Wii Fit, that production costs on that likely have dropped a lot as things tend to do when you're mass ordering like a bazillion of them.
