I see what you are saying. The way I made mine and the way SQWIBS made his is different. I use the crockpot to heat the water. The crockpot is then cycled on and off by the PID controller to regulate water temp. Mine has three components: PID Controller, Power Switch, Power Outlet.
Although a good idea to know what you are doing when using electricity, I disagree with dcarch. This project is as basic of a wiring project as they come. Follow the instructions and its easy and safe.
Here are step by step instructions:
Here is a link to my part list. I ended up NOT using the Solid State Relay.
Added bonus: I am able to connect my electric smoker to the controller and allow the Sous-vide control control my smoker...