We started off with a weekly $25 and monthly $50 "editor of the ..." contest, which is way more than organic posting rewards could provide consistently. That didn't work out for a combination of reasons, but in the end it just wasn't enough to pay enough people. And spreading the few rewards it gets would be incredibly difficult to do fairly, as contribution quality varies wildly but is also subjective to a certain degree.

There's no money to be made with a wiki. It'll either be a project embraced and maintained by a dedicated community, or not reach its full potential.