I have and use hand held radios. They have a range of maybe a couple of miles and run of three AA or AAA batteries each. I have maybe three sets of two, and have managed to adjust the frequency setting so they all match up. So I can use three or four say on the same net.
Maybe Amazon, just search for handheld radios. Dont have to be expensive. The range will vary a lot with the surroundings. In a city around buildings much reduced, open flat areas go to the max. All sorts of uses.