How much does a new one cost? I had one many years ago but sold it with everything else when I got divorced before it got old, so can't speak to the longevity. But it worked good while I had it.
KK makes a pretty darn good finish mower. At least I think so. A relative had one and pulled it behind an 860 ford to mow 4 acres for about 8 years before they sold the place and equipment. As with any mower, it will occasionally need a belt, and spindle bearings replaced. Other than that, as long as you keep oil in the gearbox, there isnt much to go wrong.
However, the price seems high to me. Especially this late in the season. But that could just be normal for your area.