When I looked at these kind of deals before they seemed like a rip-off - yeah, sure you'll get your wii, but from memory, the deals I saw were like:
a) free phone, £30 a month
or
b) Phone costs £200, £30 a month, and free Wii
Well it doesn't take a genius to figure out that you're still paying for the Wii - how much it costs you in real terms you'd have to weigh up against the cost of buying one from somewhere else...
James