The ADT Self Setup system is a DIY security system that integrates with Google Nest and, while it doesn't replace Nest Secure, it's good.

Google and ADT have officially teamed up to launch a suite of ADT security sensors and products that integrate neatly with Nest products. You can control all of your ADT gadgets and Google Nest ...

As for pricing, ADT is selling just the Smart Home Hub for $179.99. There's a Starter package which adds a Google Nest Doorbell (battery), four door/window sensors, and two motion sensors for $479.99.