Amazon offers Prime members the GE Personal Security Alarm Kit, model no. 51107, for $16.97 with free shipping. (This price shows at checkout. Non-members can spend $35 to qualify for free shipping; otherwise it adds $5.01.) That's the lowest total price we could find by $9. This wireless alarm system features a door alarm with keypad and three window alarms, all with 120-decibel alarms.