It depends on what you want and where you want it.
Doing it on a case to be made is not a problem. Doing it on an existing case is a problem.
I have an embroidery factory a couple doors down from me and I can get just about anything done on vinyl, fabric and leather. If it's a one-off type deal then there will be a setup fee which varies depending on the amount of work involved.
You can find many places on the net who will do patches for you that you can glue to your case and if done right it will look as if the patch is embroidered on the case.