I plan on buying the refurbished ones from Nintendo. You can get the Nunchuck/Wii Mote combo for 25, with 5 dollars shipping.
The reason I am backing this is because I have seen a lot of CAGs on this forum comment that they have ordered refurbished controllers, and systems, from there and they are basically open box new. You can't tell that they are used.
Also they have a one year warranty. That's longer then any other refurbished product on the market as far as I know.
Other then that, unless you buy the knock off ones from eBay or Amazon for around 15 to 20 you're not going to find any sales, sadly. I've been checking since before X-Mas. The only sale I have seen was the one at Sears where they had the official ones for 5 to 15 dollars a piece and the Nunchuck for 4 bucks.
There are third party options like Afterglow or Rock Candy. You can get the remote for about 15 to 20 bucks going that route brand new, but I personally have never used one before. My brother in law has an Afterglow X-Box 360 wired controller he has had since Christmas and it works ok.
Sorry I wasn't of more help but honestly the refurbished ones from Nintendo Store are your best bet, money wise. Chances are slim but if you get a dud, return it.
Good luck though my fellow CAG, and happy hunting!
Oh yeah, you might can get a nice deal on a new or used one by checking the trading forum here on CAG. I'm sure someone has a good used one for sale/trade.