From the Pictures on the website I can tell you will need the following
Front Fender
Passenger door
Rear Quarter-This is the worst-these are not bolt on they are welded
Rear bumper
possible front bumper
front control arms/ball joint/bearing
rear control arms/bearing/possible hub carrier and CV joint damage
new passenger exterior mirror
front side marker light
rear tail light
potential tornau cover damage-this will goof up the soft top
all lower cladding
possible battery damage-increase liklihood of electrical problems
new hood.
I would not buy this car. If it were the front and the passenger door, that is not a big deal, but when you get into that rear fender area, this is not something you can do in your garage. If you are to have it repaired you will pay big $$ for the work. Also there could be damage to the mounting areas (structural) for the door, and the fender. The hard top is likely missing too.
It is a well proven fact that a car all in one piece is worth less than it's parts. Replacing and repairing this car will likely exceed 10k. The 129 is not cheap, nor are the parts for it. You will find they are superb autos, but you pay for it. I love my car and honestly if it were ever wrecked, I would replace it. I drove a car that had been repaired from what was called "light" damage and it was a horrible experience. It shook, rattled and didn't feel like a mercedes at all.
If you are looking for a bargain shop on Ebay and have the car checked out. This car will end up costing you about 16k to purchase and put on the road properly.
Look at this, a one owner texas car and a 1997, with just 10k more miles than the one you are looking at. $15,950.
http://cgi.ebay.com/ebaymotors/1997-MERCEDES-SL500-CONVERTIBLE-1-OWNER-w-HARDTOP-L-K_W0QQitemZ4586435294QQcategoryZ6338QQrdZ1QQcmdZViewItem
The 97 has the newer interior, the improved top controls, improved fuel injection, and belt tensioner. It is also an ODB II car. A more friendly car for the mechanic if you ask me.
Save your money and get what you really want. You will be a lot happier and a lot better off. Don't forget the car you are looking at probably has a salvage title as well, these cars are worth nothing. They are really just supposed to be sold for parts. Sorry to damage your day, but I was thinking of getting a salvage one too and fix it up, but instead I kept saving my money and got one that was all in one piece. Good luck!
Brian