Where do I buy a transmission interlock solenoid for 2008

I have difficulty getting the car in and out of park. Sometimes, I am unable to remove the key in park. I have been told to replace the transmission interlock solenoid near the gear shift on the floor.

I have a 2008 Grand Prix base.
thanks

Before replacing the part, I'd check the wiring going to the shifter. I wouldn't be surprised if you found the broken wires, they've had some issues with that.