Do I just replace the brake light switch?

 

Have you checked the bulbs?
Do you have any power to the bulb sockets?
Have you done any trouble shooting?

 

I don't have the car in my possession yet (I will be buying it this weekend).

I imagine the current owner has replaced the bulbs. He told me it was probably the brake light switch, I'm just trying to confirm it.

Is there another possibility?

 

Installed new bulbs and the brake light switch (aka stoplight switch) and it took care of the problem.

For searchers:
1) Check bulbs (if okay, go to 2)
2) Check fuse (if okay, go to 3)
3) Replace stop light switch