You could buy a server or you could build one yourself.
Plex is media server software for Windows, Mac and Linux. Plex bridges the gap between your computer and your home theater, doing so with a visually appealing user interface that provides instant access to your media.
There are three great things about Plex, the first is you don’t have to dedicate a whole computer to Plex. You can install it on your “Windows” or “Apple” machine just as you would install any other application and share the media on that computer using Plex.
The third is “MyPlex” a web based application that enables you to watch content from your server on the road. You can remote control many functions of your server with MyPlex. You can also save videos form YouTube, Vemio and others to your MyPlex by using the Plex Bookmarklet which is a great way to watch YouTube videos on your Roku player (or other players).
Amahi makes it easy to setup a server on a standalone PC. When your Amahi server is complete you can completely remove the monitor, keyboard and mouse. Installation is pretty easy but it requires some intermediate skills to get it going like knowing how to download and burn a disk from a ISO and knowing how to copy and paste.
Amahi is modular. You can run application on a Amahi server such as “Transmition” a BitTorent client (to download media and other files). Backup the files on your Amahi server to the cloud or to any remote server with “CrashPlan“. “phpMyAdmin” to manage “MySQL” databases, DLNA a very fine streaming media software and hundreds more applications.
Besides being an easy to setup file server Amahi has an additional side-effect. Your Amahi server can become your DHCP server. The main benefit of this is wireless devices connect right away to your network. You never have to powercycle (unplug and replug in the power) your router again to get wireless to work.
I recommend booting to a thumb-drive to start the server
Free NAS is open-source server software based on the Free BSD operating system (a UNIX variant). Free NAS