Before you get all mentally committed to that (overpriced) Kama, talk with Tommy or Jerry at Affordable. Parts availability is one thing, but if you're not comfortable being your own diesel tractor mechanic you need to be sure whatever you get has service available within a reasonable distance. Chinese tractors are tough little beasts, but like any piece of farm equipment they will break and they will need fairly constant service. That is just a fact of life. These tractors use straightforward 1960's or so technology for the most part, but diesels are a distinctly different critter than a gas engine. Whatever tractor you get, you need to get ALL the manuals for it. My Jinma, for instance, has four manuals: Owner's Manual, Tractor Parts Manual, Engine Manual and Engine Parts Manual. Without all four, it would be a huge challenge to work on the thing.
Another thing about Chinese tractors - they need to be properly set up and serviced before they are sold the first time. All fluids changed, clutch set, valves set, bolts tightened, etc. Not all dealers do this, and many Chinese tractors were brought into the US as "crate" tractors and assembled by the purchaser - usually without much if any knowledge of what is required. Failure to properly setup and maintain one of the machines will usually result in an early demise or constant problems. This is one reason I recommend you talk with dealers like Affordable, RanchHand Supply or ArtTrac - all are reputable.
The guy with the Kama said he changed all the fluids at 100 hrs. Did he also set the valve lash and re-torque the head bolts? These should be done at 50 hours and again at 100 hours and then again at 250 hours. The oil should be changed every 50 hours unless a laboratory test shows it can go longer. All fluids should be changed again at 250 hours - was this done? These really are pretty critical maintenance items on any Chinese tractor.
Some things to consider before you make the leap. Hey, you're only 62; you've still got time to make a carefully considered decision, not rush into anything. (grin)