how much bandwidth?
if its dsl/broadband or less you can build or buy used stuff for well under $100 to do that, probably $50 or less if you shop around,even a 8-10 yr old P100 system can easily handle the upload speeds of broadband
unless your going be running a very involved and serious CPU intensive database based website you wont need anything special for that at all, and old hardware usually works quite well with any of the BSD's or linux
64mb ram is plenty if its console only based admin on the server
ethernet card
cheap $5 vid card
small hard drive at least 500mb + however much server space you need
nothing special really