I bought this in July and used it for about an hour! You can use it immediately by plugging the receiver into the AUX input of a built-in amplifier speaker! The microphones require two AA batteries each! I will send it in the original box as shown in the picture, so I cannot offer a discount because it will be sent via regular宅配 (courier service). If you don't need the box, I can send it in a more compact package and offer a 200 yen discount! Please comment before purchasing m(__)m