Amazon offers the second-generation August Bluetooth Keyless Home Entry Smart Lock in Dark Gray or Silver, model no. ASL-02, for $182.99 with free shipping. That's the lowest total price we could find by $11, although most merchants charge at least $229. It's compatible with most standard deadbolts, and works with Bluetooth-enabled devices to sense your approach and unlock automatically. It includes three mounting plates and three lock adapters; four AA batteries are required (and included).