Non-profit doesn't mean non-revenue. They don't have to pay their investors, but they certainly need to pay their developers.

Most nonprofits don't generate "revenue" from their "product". They provide a valuable service and get paid by people who agree with the mission.

Based on comments in here and people willing to pay I wonder why they haven't got the Wikipedia route of getting donations, would that piss off a lot of users? I do think most people would understand a non-profit needs donations.