https://store.google.com/product/stadia_controller
Will allow you to purchase just the controller.
https://store.google.com/product/stadia_controller
Will allow you to purchase just the controller.
You only think you don't need more Chromecasts... soon, you'll be like me and have them hanging off everything in your place that has an HDMI Input.
Controllers come super fast. I ordered one on like a Friday and had it by Wednesday.