I've looked around a lot, and I don't think we'll be able to get a decent centralized server for less than $100/mo. Obviously that's a lot for one person to spend, but if we get 4 people in on it, it'd only be $25/mo.
I figure we do something like this:
$25/mo - your very own, complete, 32-player server for matches, public play, whatever you want.
$5/mo - login access to change maps on the pubs.
These servers will be run on the racks er33t used to have, so I'm hoping they'll be top-notch. If not, we'll find another host.
If we get more than 4 people, the extra money will be either donated to help cover server costs of other free projects and/or kept in reserve for situations like exceeded bandwidth, people dropping out, etc.
If you abuse your administrative privileges, your server or login will be terminated.