Radio frequency signal transmitter
Vishay (nee Sharp) IR receivers perform with excellent range outdoors (30m).   Check the frequency of the emitter before ordering a receiver. Popular choices are 36, 38kHz, 40,... These are stock at Digikey for &lt;&lt;2$ in the same case.

http://www.vishay.com/docs/82484/tsmp1138.pdf

one with a 45m range is this one for same price.

http://www.vishay.com/docs/82489/tsop322.pdf