Likely scenario IMO= $30: game + MotionPlus, $20: MotionPlus
Aggressive(r) pricing by Nintendo IMO= $30: game + MotionPlus, $15: MotionPlus
I can't see Wii Sports Resort costing more than $10-15, considering the original one was FREE. But it is gonna have 10 games, so that's good.
Nintendo will still wanna make money off it, and I can't imagine a technology that was too expensive to mass produce 3 years ago costing $10 now.
# of games above 75 on Metacritic (including downloadable):
360: 241 DS: 144
PS3: 152 PSP: 126
Wii: 85