iSmartAlarm's $150 Starter Package comes with a CubeOne hub, one door/window sensor, one motion sensor and one key fob. Add an iSmartAlarm Spot or iCamera Keep Pro camera to the system and connect it to IFTTT for advanced automations with third-party devices. iSmartAlarm doesn't offer professional monitoring.
Nest's $399 Secure alarm system starter kit includes one Guard hub, two Tag key fobs and two Detect door/window/motion sensors. Professional monitoring services will be available via Moni, but not quite yet.
Arm and disarm the Secure system with a PIN code, a Tag fob or through the Nest app. Add Nest cameras and other devices to expand the system.
The Scout security kit comes with a $129 hub, a $29 door/window sensor, a $49 motion sensor and a $40 water sensor -- all for $247. Professional monitoring and cellular and battery backup cost $10 per month, but they're optional and contract-free. Scout also works with Amazon Alexa.
SimpliSafe's reasonably priced starter kit will set you back $229; professional monitoring starts at $15 per month. It's an optional feature, but one you'll need if you want to access any of SimpliSafe's remote security features.
SmartThings' ADT Home Security Starter Kit comes with a 7-inch SmartThings panel, two door/window sensors and one motion detector. The kit costs $550, one of the most expensive DIY systems available.
Spend an additional $200 for the expansion kit, which includes a smoke detector, a carbon monoxide detector and a water leak sensor. The SmartThings system offers month-to-month ADT professional monitoring starting at $15 per month.