Rock Auto has one for $35 right here: http://www.rockauto.com/catalog/raframecatalog.php
Just click on "Brake/WheelHub"...
BTW, you could get your car home by using the original MC. It will work, just be a little harder pedal is all... Also, you can use your original MC or even another one you may have that is froze up as the core. They don't care, just as long as it is somewhat close...
Good Luck!