My son has a Darth Vader mask that processes his own voice through some sort of mic/speaker arrangement and it comes out with that effect. It's actually a pretty close approximation. And it has a button you can push to get the JEJ heavy breathing.
Any Vocorder will give you the pitch change and you can mix in breathing with a microphone and preamp or USB microphone. Breathe (gently) on the microphone and then filter out all the frequencies below about 1000 Hz.
One of the advantages of being in LA is that we have two admin people that can actually do the voice in real time.