According to itrackr, the Wii is only at about 3% availability at the moment. That is, about only 3 in 100 stores nationwide in the U.S. actually have them in stock.
I speculate that Nintendo slowed down the production of the Wii temporarily to meet the demand of the DS Lite, which was in very high demand throughout January. I wasn't able to get my DS Lite until about 2 weeks ago; it had about the same availability as the Wii does right now.
There are a couple things you can do:
-Bookmark a lot of websites like Target, Wal-Mart, Sears, NewEgg, Toys R' Us, EBGames, SamGoody, Fry's, Best Buy, etc and check them every few hours or so to see if any units are in stock. If any are in stock at one of those places, waste no time ordering it online, because it will be gone very soon.
-Backorder one. If you backorder one, you can receive it when it is in stock again. When you backorder an item, the people that backordered the item previously and haven't received theirs yet have priority. You might as well "get in line" if all else fails. Besides, if you find it in stock in a different location, you can cancel the backorder. If it happens to ship at the same time as when you buy the other one, you can send one of them back for a refund.
This process takes a lot of patience; even if you do all of the above, there is still a very good chance that you will not be able to get what you want right away.
Hope this information is helpful.