I don't know if it's still true, but someone mentioned at some point that Dell's cases are made by Palo Alto. It's possible they're custom jobs and not otherwise available.

Dell takes a big leap into the future with today’s release — the brand new Dell XPS 8950. The refreshed lineup of pre-built PCs features all the technology PC enthusiasts have been waiting for, ...

I'm trying to replace a hard drive in a Dell XPS T500 P3-500 system. The hard drive is mounted in the oddest place. It is placed vertically flat right up against the bottom front of the case. I can ...