I have an S110, and I believe it has the same dimensions s the S200 (or at least close); anyway, my S110 is 3 3/8" X 2 3/16" X 1 1/8". I picked up a belt clip case at a show about a year ago; it was made by Western Case Company in El Segundo, California. They have an 800 number on their tag on the case: 800-310-3023 which should work if you're in the USA. I don't find a web page for them, but maybe they will send you brochures/a catalog of their products if you give 'em a call.
I'm very happy with mine. It has a metal belt clip which will NOT come off accidentally...you have to work at it to get it off your belt, at least until you get the hang of it! It has a stong webbing loop that the clip goes on, and you can take the clip off if you want to put the case on your belt directly.
Downside of it is there's only room for the camera (dimensions above), and nothing else. That's my only wish...that it had a little pocket to carry an extra battery and/or CF Card. If you're interested, I can snap a few pics of mine & send 'em to you so you can get an idea. Once I have it on my belt , I literally forget it's there, unless it's over your pocket that you want to dig into for something!
Disblamer: Not affiliated with Western Case Co...just a satisfied customer!