Kaidomain.com offers three Wireless Door Bell Chimes for $10 or less, alll with free shipping.
$10.13 RL-3915B Wireless Doorbell with Double-Transmitter
$7.46 NS-9688F Consta 3in1 Wireless Door Chime
$7.21- Wireless Door Bell-Blue #SKU847
$10.13 RL-3915B Wireless Doorbell with Double-Transmitter
$7.46 NS-9688F Consta 3in1 Wireless Door Chime
$7.21- Wireless Door Bell-Blue #SKU847