2 Logitech mice - $24
Linksys switch - $15
Cat 6 cables - $22
Padded steel chair (needed to upgrade from steel) - $12
Table from a thrift store - $30
Replacement power supply (the other one was fried) - $50
Speakers - $12
Surge Protector - $18
I rounded it up to the dollar.
If using this as an example for your own home server, you will possibly need to add the cost of two desktops, and hopefully won't need a extra power supply.
UPDATE: Just a note for the Linux server flavors, I'd highly recommend CentOS it seems to be much more geared towards servers than trying to force Ubuntu or Fedora to act like one.