Those cases (AT-HPP5) are no longer available from Audio Technica. There are some knock-offs on ebay from China for cheap...but instead of waiting six weeks for something of questionable quality, I keep mine in an Eagle Creek Protech Half Cube:
As far as durability, they are well made but probably deserve a little pampering. I got a spare gimbal joint ($6.00) from Audio Technica and so I use them portably with no concern as I have the spare part that is most likely to break.
Edited by wolfen68 - 2/24/13 at 3:16pm