"My casio wrist watch reads the atomic clock signal, ....., then something tells me you can build it with very minumual parts."

Wrong assumption. Just because one percieves it is simple, does not make it simple. In all these apparently simple solutions there will be hidden somewhere a very critical component or firmware that is difficult to reproduce minimally, normally.

If you are planning to build a radio from scratch, I doubt if you can get such components. The level of integration is so high nowadays that the normal tuning coils, HF transistor based oscillator circuits required for the SuperHeteroDyne tuning etc may no longer be available. Maybe you can get lucky if you search for hobby electronic kit suppliers. Portable transistor radios and Audio amplifiers used to be favourites with these guys...

Raghu