They're easy enough to scratchbuild; I put one in the tornado chaser I'm building. (Unfortunately, I have no digital camera with which to post photos.) A small rectangular scrap of plastic painted flat black (except for one end) serves as the body of the radio. Cut out a piece of .010 styrene sheet sized to fit the unpainted end of the body; paint that flat or semigloss black. This will be the radio's control panel. With my control panel, I cut out a small rectangular hole, painted a scrap of clear acetate silver gray, then glued the acetate unpainted side to the control panel. (The clear acetate replicates an LCD.) You probably might not want to get that carried away; simply painting an LCD on the face would probably work too.
Next, you glue the control panel onto the unpainted end of the radio's body. Add a few scratchbuilt knobs made of stretched sprue cut to size. (Go to the aircraft forum and look for chukw's excellent Helldiver build, which unfortunately changes its name, so look for his name rather than a title. In one part, he scratchbuilds an excellent radio, including radio knobs made from stretched sprue.)
Make the microphone from a tiny bit of plastic scrap cut to shape, drill a tiny hole in the base and paint it flat black. Add a cord made from tightly coiled fine black wire bent to a "U" shape. Attach the cord to the mike, then the mike to the radio; allow the cord the hang realistically.