price paid £12.99 They work really well, I have 2 in a large house 1 about 10 mtres from door bell and another about 30+ mtrs away, no problems. It is loud enough , some melodies louder than others. Some nice melodies and a couple of naff ones , but there are 16 to choose from, which I think are plenty to suit everyone (button on side of ringer to change melody, you can choose a different one for each ringer). There is also a simple ding dong, if you prefer. The battery for the bell can be purchased cheap enough from ebay , not sure how long they last. The bell button is good and has a reasuring click when pressed, unlike some of the rubber bell buttons.
If your buying 2 sets as I did, one for me and one for parents and like me you live close together (accross road) you may need to change the frequency, so they dont all start ringing together . All you do is remove 1 of the 4 small clips in the bell and the same in the ringer and thats it. they will not interfere with each other. Overall seems a good product and value for money, smiliar product at Argos is £25.