The Wii is $249 retail. It comes with the system, one controller, one nunchuck, and Wii Sports (game).
FOR SURE things you should purchase for the system when you buy it are: extra contoller for about $40, (one comes with the game Wii Play, which is $50, so it's worth the extra ten bucks to purchase Wii Play) and one extra nunchuck for $20. Optional to buy at the time of purchase is a Classic Controller for $20 -- if you're going to download older Nintendo games via the Wii Store (online).
If you have a television with component hookup (i.e. any HDTV, or any television where there's a component video input) then for sure get a component cable for the Wii, which greatly increases the resolution. It retails for $30, but you can get one off of monoprice.com for like $5.
http://www.monoprice.com/products/pr...seq=1&format=2