I am trying to design an alarm clock with an Arduino, but with the off button in another room. I am trying to figure out ways to make a sensor transmit its signal to the base Arduino. I could have two Ardunios connected via Bluetooth, but that adds the cost of another Arduino. Is there a button or sensor available which is Bluetooth or other wireless communication compatible? Or if anyone has any other solution ideas as well. I should note that the sensor and Arduino will be separated by a wall.
I would use nRF24l01s and a 3 volt pro-mini ($4 - $5) in the other room.