There is another product out there called Lisaver. It pulses the motor, which is more noticable that the buzzer sound or an LED. I know since I made my own LVC device with a buzzer. Here is a link to the Lisaver:
http://www.flydma.com/lithium/lithium.asp?path1=lithium
SH Z-Car, Custom Crawler, 8s Savage,
12s XTM XLB 1/7 buggy,
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Belt-Drive Mammoth ST 1/8 truggy, 4s 17.5 MM Pro HPI Blitz