New guy here..help on a 98 E300 TD

I have a 98 E300 TD with 200K miles, I had a company truck that I drove every day for the past 10 months.  I left that company and started driving my E300 around again.  I started and drove the e300 at least once every 2 weeks, usually a little more often during those 10 months.  I live in San Diego, so there really is no cold weather to deal with. 
 
I brought it to the dealer because the check engine light came on and I needed an oil change...and this is what they told me:
 
Cigarette lighter is broken replacement cost $125 (part $60, labor $65)
 
Mass airflow sensor is the cause of the check engine light: $760 ($439 parts, rest labor)
 
Oil change $75
 
Lower ball joints are cracked $408
 
Rear differential is leaking (never seen a stain on my drive way) $1033
 
Need a belt and belt tensioner ($453) (just replaced about 18 months ago at another dealership)
 
Left head rest motor is not working and needs to be replaced for $440
 
Is this outrageous, or are they in the ball park on all of these things.  Can I get it done at an indy mechanic for cheaper?  I just feel like I am being absolutely ripped off. 
 
Thanks