Ds10 bought our Wii (and gamecube), and everyone shares (it was ds's idea, actually). Dd12 bought the extra controllers, and some other accessories. They've all chipped in for games, unequally, with no problem.
It's in our living room, and although they've received games as gifts, everyone plays everything. I bought the Wii fit, just because. I don't know if it's because they're close in age, get along great, or because we're a big family, but this has never even been questioned. I asked them if they would rather receive individual, smaller gifts from grandma, or a couple of Wii games to share, and they all said they'd rather share.
Since there are 5 of them, the only way they got expensive gifts is if they share.