1997 Other Saturn Models Stalling

The Saturday that just passed, my car died while I was driving. I pushed it into a parking lot and checked under the hood. My belt tensioner was shot. I had the Canadian Tire across the street fix it for me and now the car is stalling out and the check engine light is coming on due to some "cam sensor" that isn't there. Now the mechanic is charging me another $400 to clean and readjust the throttle body and says the sensor will cost another $500 at least. Any of this sound off to anyone else? The car is a 1997 Saturn SL1, automatic. I've got a little bit of knowledge when it comes to the mechanical side of life and something about this isn't sitting right. Just curious if I'm getting hosed.