So, for over 20 years, there has been a 120V limit switch in the basement of my grandparents house that turns on a light when the door to that small room is opened.
This switch is a plunger with a spring. the plunger is about 1-2cm in diameter and has a throw length of about 5cm. the light is on when the plunger is not pressed in.
I've looked for similar switches and they all seem to be horribly overpriced. Most of the 120V switches i see are between $50 and $75. I've seen a few on ebay for $25ish. toggle switches can be had