You can save even more by making the splitter/power blocker yourself. It's simple enough that you can even do it by twisting instead of proper soldering, as long as you have a couple of cables you can sacrifice. On top of that you can get a cheaper hdmi-usb converter instead of using MIPI. They don't recommend it because the latency is bad and it's awkward, but it's still serviceable, especially if you only use the KVM for quick tasks. Doing it this way you could make the thing for only about ten euro cost on top of the pi.