Okay, I finally managed it to buy me a new iPod Classic 80GB since my 2nd generation iPod seems to have some gremlins.
As I know that Apple does no longer deliver a bag, I through it should be easy to get a bag from a 3rd party. Boy was I wrong.
You basically get everything, silicon slip-in cases, sports armband cases, charge cases, kitty cat cases.... But I just wanted a simple case. Means: Put the iPod in for transportation and put it out if you plan to use it or not.
Believe me or not, the only simple case I found was one from Marware: Sportsuit Sleeve for iPod classic and video.
Sometimes the simple things are just so hard to get.