Well, if you see someone wave as you drive down the road, be sure to wave back because that's me driving in the other direction. I prefer to buy used, but ONLY from someone who maintains their equipment well. No problem there, because that's pretty easy to tell. A glance around the property as I drive up is usually enough. Once I get there, a look at his equipment and maintenance tools and records will tell the story. Yes, they probably are asking near new price. That's OK by me.
If none of that is right, then I'm not interesting in negotiating price, I'm simply saying goodby and driving away. No reason to even talk price because that person doesn't have what I am looking for regardless of price. But that's usually no problem; most people take excellent care of their machinery - or today they have the dealer do it. In either case, the records are complete.
How used means it is used too much? Well, my preference would be to buy right after the warranty has expired but before wear sets in. Around here that would be somewhere in the 3 to 5 year old machine with between 250 and 750 hours. Those hours are nothing on a machine that should go another 4000 hrs easy with little more than routine maintenance - but I'll probably have someone want to buy it from me before that happens. And if they don't, a tractor with 4000 hrs is far from done. It still has real value.
As for price, that's always negotiable & depends on a lot of things. I might even go new price for the right one. In fact I have done just that. Price is flexible because saving money is not my goal. I'm buying used because I'm after proven reliability and proven performance; not some a brand new machine with unknown problems.
Look at it this way: A new tractor warranty is something dealers offer to used to cover manufacturing mistakes, right? Well, I'm not interested in hassling with manufacturing mistakes. Let someone else waste time wrestling with that. I'm interested in the machine AFTER that has been done and the machine is a proven worker.
rScotty