I think the only way to do prizes as big as the ones mentioned are by setting up a donations system... The issue with that is we don't want Ninty on our asses because they think that we're charging for Nintendo properties
Gotta think about the legal ramifications of having donations on a fansite... (Or rather, we have to read up potential legalities behind that).
All in all, if we did have something like that set up, then we could do a major contest once a month or something.