I think your best bet is to look into woodworking stores. Machinery, specialty cutters/blades/etc are what they are known for, and many even deal in furniture hardware. Maybe checking a place like Rockler should be able to point you in the right direction if they cannot help you out directly. A simple Google search for woodworking stores and hidden hinges should also give you a pretty good start.
If that is the only door with those type of hinges, or since it is somewhat concealed, what you have is a variation of a no-mortise hinge. The main difference between yours and a standard off the shelf no mortise hinge is your allows the pivot pin to go behind the edge of the door, where the standard ones have the pivot outside the edge. This will mean you will need to replace both hinges so the hinge pins line up.