they are 160$ I believe he sells Timbo's APPS, OEM prices will scare you as they are 400-500$. the Timbo (williams switch) is more robust and not susposed to suffer the same fail rate as the OEM one,
I have Timbo's apps on mine, and have installed them on 2 other trucks....works good no issues, instructions are simple and easy to follow.
did you get a code for a APPS/TPS failure?