This is what I am taking about, and it's $6.
Case wise I think this will be better, as sometimes you want a case with a bit of give to lessen the impact and not to have your headphone get knocked around inside the case.
Oh, that interconnect. I'd try it, if I had not got a custom pure cryo silver interconnect.
As of that case, my M-100's, as you already know, come with a pretty good case for them.