I bought a 3 stalk from Gaudin Porsche (on line) in Feb 2012 for $177.91, shipping included. Google them. I'm in NC, they are in Nevada.
I replaced it myself, and it wasn't bad. My only mistake was I reconnected the battery terminal before reconnecting everything, and I ended up with a check engine light that I had to get reset. I followed this you-tube tutorial:
https://www.youtube.com/watch?v=hux78ZoPcAI
It was almost four years ago, but from what I remember it wasn't a hard project. I wish I had done the four stalk and enabled the OBC.