'86 420SEL help a serious newbie out

My mom has a 420 SEL that's in great cosmetic shape considering the age, the only blemishes are a couple door dings and a crack in the dash (probably from sun). I am a TOTAL newb when it comes to these cars, but I'd love to buy it and maybe make it a DD if it can be done.

The cars ODO shows 160k but documentation from when she bought it 10 years ago shows a rebuild at ~ 120k miles. The car has not run for at least 3 years and I can't get it to fire up. The reason she stopped driving it was the seats were not confortable for her back anymore and the radio stopped working, or when it did, it would just make really loud screaming type noises out of the speakers.

What should I expect to spend to get it on the road? or, conversely, what might this car be worth as-is?

Thanks much for any help,
Matt

PS if there are other forums that might help me, I'd much appreciate some links.

THIS CAR IS PROBIBLY WORTH ABOUT 3000 MAYBE. THERE IS REALLY TO MUCH TO LIST THAT COULD BE WRONG WITH IT FROM OIL LEAKS TO RUNNING CONDITIONS TO SUSPENTION PROBLEMS MY BEST ADVISE TO YOU IS UNLESS YOU HAVE MONEY TO REPAIR PROBLEMS AS THEY ARISE SELL IT. CAUSE MERCEDES PARTS ARE NOT CHEAP IF IT HAS SIT FOR 3 YEARS I WILL NEED A SET OF INJECTORS AT $400 INSTALLED IF THE TRANS DECIDES TO GO OUT ON YOU THATS ANOTHER 3400 AND IF IT NEED A TIMMING CHAIN(THAT SHOULD BE REPLACED EVERY 90K ON THE 420 SEL) THATS ANOTHER 1200 BUCKS S I HOPE YOU GOT A FAT WALLET