Well, if Yakuza 3 breaks even at ~500.000 copies it's obvious that the average Wii game needs much less.
It's often reported that Wii development is 1/2 to 1/4 of the cost of HD development, so for projects the size of Yakuza 3 (which aren't very abundant for Wii sadly) we can say that it takes 125.000-250.000 copies to break even.
I would put a game like MadWorld in that category.







