Ho ho ho
It is in a company's interest to see that the market clears, i.e. that it sells a unit to every single customer that's willing to pay the price it demands. If customers turn up with cash in hand but they've got none left, there are three possible explanations:
1) The supply can't possibly be expanded to meet demand. In today's world this can only apply to the few goods that can only be made properly by artists or craftsmen. A Wii is a generic electronic good that can be churned out by factories all over the world. Forget this.
2) Nintendo are too incompetent to work out how many Wiis are going to be bought. They've been one of the leading console manufacturers since the NES, and have successfully kept with the times even as Sega et al have fallen by the wayside. Not a chance.
3) It's a marketing ploy to sell more Wiis to panicking parents and others convinced that they've got to buy this now or it'll be too late. If there is a shortage at Christmas it will magically disappear as people flock back in to the stores in January on the back of great publicity shots of snaking queues and fighting housewives. And it's a ploy which lazy/gullible hacks are only too willing to support. Yep, sounds right.