Can anyone give me some idea what it will cost to repair my Silverado z71 pickup?

Question

The alternater is producing DC instead of AC (?) and is causing the lights on the dash to strobe.  Also, the sensor is out on the 4-wheel drive so I can't engage in 4-hi.  The bendix on the starter doesn't kick in to start the truck sometimes.  That's all we know for sure right now, but we're new to this truck and have no idea what these repairs should cost.