Here is a thread about chain cases.
They are very hard to mount to frames and cranks not designed for them.
That one is made by Sogreni, and probably going to be the best fit for your bike. They don't retail them in the U.S. but they will send you one direct. After shipping and customs it's going to run close to $100. Look at it closely. It would not be hard to fabricate, and for considerably less. A couple of P-Clamps, some solder, brass tubing or dowel, and an hour or two; you can make one that will actually mount for under $20
--A