As far as the cost goes I think it gets back to Robert's original post...i.e. 25GB of files, 100GB of monthly transfer. I can't be certain, but there's a good chance Robert's running his own server (seeing as how he does this as a business), so it's a matter of asking how much the annual cost is. I can only speak from my own personal experience but my site's server costs me $55 a year. For that I get 10GB of storage & 300GB of monthly bandwidth transfer (but then, I don't need a lot of transfer as there's nothing to download from my site...it's purely informational).
That being said, there are some real good deals out there (I'm probably going to switch servers after 10+ years when my current contract's up in April)...even GoDaddy can be had for $3.49 a month ($41.88 annually) for 100GB of storage and unlimited bandwidth. There's even some better prices from servers you've never heard from to be had, but I think that would involve some research to find out about up-times and what-not.
If y'all are really interested in keeping it going, I'll chip in as well. Throw 5 of us together at $10 a head for a year and it should be covered. Or maybe not...my knowledge of server prices is limited. I do know a fair amount of coding but I know nothing about how to make a forum work.