Newbie question
 

HI folks! I've had my 99 ML320 for about a year now. Just recently my ETS lights comes on when car is cold and also a light vibration in the driveline. Now I've taken it to the the dealer and have diagnosed that the transfer case is at fault and also the steering angle sensor. Now the vibration is from the transfer case and the ETS light is from the sensor. I have an extended warranty but only covers the transfer case but not the sensor. They quoted me about $1100 for the sensor, labor, and alignment. Does that sound about right? Also, is there any other place where I can purchase the sensor and how hard is it to change? I am mechanically inclined but have never worked on an ML before. Any help would be greatly appreciated. Thanks in advance!