My 2019 model has 25K with no issues. The in-line-4 engine is powerful and silky smooth. I'm 170lb. The Z900 front forks are sprung too soft (for a 140lb rider) and the rear shock is sprung too hard (for a 200lb rider.) The previous Kawis I've owned only needed less expensive Race Tech front fork emulators. The Z900 forks, however, do not accept emulators (only one fork is functional for compression) and requires fork inserts. I went with a set of Andreani from Jim at Catalyst Reaction. For the rear spring, I added a set of Shad luggage and a tool kit to weigh down the rear.
When new, the throttle felt snatchy to me (no riding modes). I used damping grease under the throttle grip to slow it down a tad.
Accessories are cheap because so many Z900s are sold world wide. For example, my Z900 logo radiator guard I bought on Ebay for about $35 (I don't remember the exact amount.) Also bought a taller wind screen, bar riser, shorty levers, carbon fiber look plastic body pieces for cheap too. A lighter muffler is next.