Senior Design Project help: Connecting a PID system to Arduino

I was wondering if it was possible to buy a PID system, and interface it with arduino. Or is a PID system something you can build from scratch on an arduino breadboard? Not sure if you "buy" a PID already programmed, or if you build one from scratch. As I am not an EE major, I would prefer to buy one.

The reason for the PID:
To control the temperature of a soldering iron, using a thermocouple to give feedback on the temperature.

The idea:
Have the thermocouple as the input to the PID device, and the soldering iron wires(?) as the output. The arduino program will regulate the soldering iron temperature based on the feedback from the thermocouple- which will be placed at the tip of the soldering iron.

^ Is this even possible?

Thanks!

There are a lot of industrial controllers that implement PID control. Interfacing with them will probably be more effort than implementing a control strategy in the Arduino. I would suggest a strategy that involves PWM output to control the soldering iron and some sort of feedback loop to determine the PWM duty cycle. Proportional control without feedback might even be sufficient if PID control is not a requirement for your application.