Gotta agree with GAKubotaFan...we're thrashing through the same issues r.e. new vs. somewhat used for a car. We can't afford what we want new, so we have to compromise on getting a used vehicle like the one we used to have (some...person smashed into my wife's car, totalling both).
Anyway, trying to come to a point here /forums/images/graemlins/crazy.gif, we can afford used for what we had or new in a less expensive vehicle. We haven't decided for sure, but are leaning towards the new, less expensive option for the same reasons mentioned; you never know how the thing was treated.
In 30K miles on a car or 35 hours on a tractor it is possible to cause some severe, long term damage. Was the engine run dry on coolant? Out of oil for a few minutes? There are so many things that can cause horrible, long term problems that you'd never know about that I shy away from them.
But you can also find great deals. I'd suggest you try to discover why someone got rid of a great tractor with so few hours. Hopefully you can get a good explaination...