People are really exaggerating on the hidden costs. Yes, there are games that require extra, but the same can be said about the PS2. I paid like $80 for GH2 when it released, which only came with a wired guitar. The PS2 also didn't come with its own memory card, and required a multitap for anything more than 2 player games. It didn't come with a game, either - the Wii comes with Wii Sports packed in. Then there's internet access... really, the PS2 is a poor comparison.
New Super Mario Bros Wii, Mario Kart Wii, Wii Sports, Mario Party 8, and Wii Play, only require the Wii remote. None of the top selling multiplayer games require nunchucks, even Smash Bros and Mario & Sonic. So, getting 3 extra Wiimotes is actually cheaper than 3 extra PS3/360 controllers, MRSP at least. People claiming they're forced to buy 3 nunchucks are being misleading - what games are they playing that require this, exactly?
The only real "hidden costs" are the batteries. It cost me under $30 for enough batteries to supply 4 controllers. Annoying, maybe, but I prefer it to the PS3 controller which requires you to connect the thing to the PS3 for a recharge. It isn't uncommon being forced to sit in front of the TV and play wired when enough people in the house actively use the PS3. (I try to avoid this by having my laptop nearby, though it's still a pain)
