Go into your local Porsche dealer, tell them your brake lights are not working. After you have the discussion about fuses and bulbs, then you will eventually get to the (hydraulic) pressure sensor that controlls brake lights.
Buy the Porsche part and you will spend $40+
However, that same part is used on the VW Beetle from 1970 - 1974, yadda yadda, etc.
Alternatives to the Porsche part are:
WORLDPAC brake light switch N3150-15117-Brazil
(Interesting notation, because Brazil bought the tooling for the Beetle, and they are still producing it down there, and they probably have a lot of them with brake lights too, lol).
BWD Automotive, S567 with suffex of v08217 and a bar code reading of 33086 02768
Here is what they all look like, this one happens to be the BWD unit.
These are identical units, threads are the same, appearance is the same, and they are each three pole units. The two non-Porsche parts are $15