What would be the ideal hardware setup for pushing lots of bandwith on a tube site?

We have ever-expanding cloud storage where users upload the movies, then we have these web-delivery machines which cache the FLV files on its local harddrives and deliver them to users. Each cache machine can deliver 1200 mbits/s , if it has SAS 8 harddrives. Such a cache machine costs us $550/month for 8x160gb -- so each machine can cache only 160GB at any given time.

If we want to cache more then 160gb , we need to add another machine..another $550/month..etc. This is very un-economical so I am wondering if we have any experts here who can figure out a better setup.

I've been looking into "gluster FS", but I am not sure if this thing can push a lot of bandwith.

Any ideas highly appreciated.

Thank you!