I bought a 1974 Oliver 1270 tractor recently for $3,000. Unfortunately the dealer didn't quite maintain the tractor and sold it as is. After investing $325 to get it rewired and tuned up (gas filters were pretty dirty) it now runs like a new tractor.
After 2 months of working with it I can say it was a great buy. Hopefully it will last. The mechanic told me they were very reliable machines if you take good care of them.