280SE 4.5 - Worth Buying?

I have recently dicovered a rather neglected 280SE 4.5 within a mile from my house, just aging away. The car has little rust and the owner said it ran within a year but developed a knock, he thought it was a rod, so a rebuild is probable. Interior is in decent shape but will take some work to be perfect.

My question is, what are these cars worth? Is it a rare model? I have looked in autotrader and the nice ones seem to be fetching a high price (12-20k). Are there parts out there for this car? Are they outrageously expensive? What about a rebuild, what is the cost of a DIY job and buying/keeping the tools (major block, head work done at a shop) verses a professional job?

The car is a Euro and has 181k on the odometer and he is asking $600. Stay away or jumpin, that is the question.

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Ross
96 C280, Greenish Black