Well you wouldnt need to spend a ton of cash on it.
-A router (if you have broadband, with only 1 PC you can use this to run multiple PCs on 1 broadband connection)
-A Spare PC with maybe at least 15-20gb HDD
-An OS (Linux or Windows, which are free...cough..)
-A web server (Apache (linux and windows) or IIS (windows only, its on all flavors of windows starting at windows 2000, i prefer the one on windows server 2003, but xp professional also has its own version)
-A SQL server (MySQL is the best choice even tho I hate its initial install/configuration method)
-PHP
-And lastly, know-how/ideas for designing the webpage, or if its a forums only deal, some sort of portal system, PHP-Nuke, Geeklog, etc..or just forum software, phpBB or other.
All of this is free, except if you have to buy the spare PC, and bandwidth, which really isnt that much, since you can always throttle down the bandwidth, easily done in IIS, dont know how in Apache.
This does not require alot of money.
For the domain part of it, you can get that for free or a small price. On GoDaddy.com, they offer
www.igclan.info for less than a dollar a year. The .com is like 3k, some retarded domain hijacking company owns that. This will I think secure us into the Google search dbase too i believe.
OR, you can get a free domain, via dynamic dns
www.dyndns.org. You can get igclan.ath.cx or somethnig along those lines.
Also once this is configured, you can just throw it into a corner, with nothing but power and a network cord plugged into it. You can log into it remotely with VNC.
I can help set some of this up, but if you want my help I recommend Windows, mainly because a) I hate apache, b) i hate working with linux, and c) i prefer windows environment and IIS is way better in my opinion.