The Byron Smartwares BY323 Wireless Portable & Plug Through Kit has a 60m range, and a chime with 4 sounds. The socket can still be used as any appliance can be plugged into the door chime and still operate. The plug-through feature means that no socket is lost - another mains powered object can be powered by plugging into the chime.
The portable chime requires 3 x AA batteries (NOT included).
The push requires 1 x CR2032 battery (included).