I'm an everyday guy but pretty old so I spent a bit of my kids' inheritance on it and an HR3584 on my L5740HSTC, but yeah it is pretty expensive. I bought mine as a package on a new tractor so got a good deal, but you ca get a good idea by going to the "Build my Kubota for the MSRP. You can get non-OEM hydraulic top and sidelink from Fit Rite, as good as OEM and if you're handy with tools you can install it all yourself. I'm not, so I had it done.
Even if you don't go full TnT and high end box scraper, a hydraulic top link is worth its weight in gold.