If the car is in decent condition other than the rust, you might get $1300
out of it.  I just bought an '81 300TD Turbo with 205k in very good
condition for $2000 with very minor rust and a few minor problems.

Offer it on Ebay, typical prices are in the range you desire.
j.

Say not the struggle nought availeth
The tires and the air conditioner are vain,
The buyer faints not, nor faileth,
And as Mercs have been, Mercs remain.
If buyers were dupes, sellers may be liars;
It may be, in yon rust concealed,
Your buyers chase e'en now the Benz,
And, but for you, possess the 300D.
For while the tires roll, vainly breaking,
Seem here no painful inch to gain,
Far back through creaks in muffler making
Comes silent, flooding in, the main.
And not by German windows only,
When bids come, come in the light,
In front the price climbs slow, how slowly,
But eBayward, look, the price is right.