Why would you not factor in the design? Goto NewEgg.com and price out some nice Lian-Li cases. They're expensive. Yes, you can get a junky finger slicer case with loud fans and tacky lights for ~$50 but that's not what I want
Why does th design matter beyond "look at me, I'm using an overpriced collection of stock hardware". It's the old saying "you can't polish a turd". Commodity hardware is always going to be commodity hardware no matter how shiny the case is.