A 300D will make a great commuter car. That is a decent price if the records show some work was done on it. Even if it needs a new compressor (a freon leak is another thing though!)
If you aren't inclined to work on it (they are really quite easy to work on!) you'll need to find a good Independent shop that knows this model, I am sure R Leo can help you. An Indy can also do a PPI (pre purchase inspection) which is highly recommended!
Go over to the Diesel forum for lots of help if you do buy it.
And if you find an A/C shop that tries to sell you on a conversion to R134A, tell them forget it unless they will install a parallel flow condensor, if they say whazzat? then find a shop that has R12 and isn't greedy. In Texas you need a cold A/C and R12 will do just that.

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!