It's what's inside that counts! You should not buy a case for its color, that's incidental. Your money should go into a GOOD case. One that will last through several upgrades. It must be sturdy, rolled edges, easy access drive bays, lots of fan options, air filter(s), reinforced PS mount. And with BTX just around the corner, maybe one of the new ATX/BTX boxes.
Don't get a case just because it has a power supply included - chances are it is underrated and noisy (electrically and sonically) and just thrown in to sucker someone into buying the case.
After you are certain all that is addressed properly, then go for looks.
Besides, unless you are going to be carting the PC around showing it off, you are likely to tuck it away someplace.
-bill
Having said all that, I just built a new PC for the wife and bought the Antec Sonata - it if gorgeous! Piano black, as it is described, and it does shine. But, except for the BTX support, it met all my requirements first. Note that the optical drives and internal 3.5 Card Reader did cost a few bucks more in black.