Depends on what kind of ride you want and how much you like to work on your own vehicle. It seems for the money you want to spend you can get into a nice 300SD, 300SDL or something a little newer, maybe 300D. If you like to work on your car and you want a rock-solid 400,000 mile car go with the w126 300SD. There are a few more choices but this is my opinion.

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'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R