We bought one from a garage sale this past summer. Battery only.
Went to SoDak for a 2 week trip. Coming back, we were in a very sudden tornado watch area.
This is what I can tell you.
You do not need a zip code for an emergency weather radio. It will pick of the closest signal to wherever you are. It will give you tornado alerts with a loud continuous sound and then voice. Also, we have a stupid cell phone. That also gave the tornado alert signal but no voice.