I paid $3200 for my 85 300td with about 135K (the odometer had broken in the recent past and showed 124k). It needed a few vacuum repairs in the vents but no rust and runs fine. Wait for a better priced one. Keep looking in your local papers, Auto Trader, Cars.com Ebay, etc. I found mine at a local Chrysler dealer where it had been traded in(even though I was looking nationally). It was mislisted as a 190 wagon on Cars.com. They knew absolutely nothing about diesels and wanted to get rid of it.
There have been a couple in our local paper in the last few months at less than 5k. There was an immaculate Burgandy colored one whose owner I saw on the street and talked to . They wanted 8700 and I thought that was too high even though it was beautiful.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13