@igwigg Don't go for the cheap no-name ones. That's what I bought first for 30€ and it had really annoying problems, especially with the keyboard just not working all of a sudden. I went with a KVM from TESMart for 190€ next and this one has been working perfectly. Looks like they released new models since then and the one I own is now 130€ only on Amazon: geizhals.de/tesmart-4x1-hks0401b2u-a2692914.html
If an older model is good enough for you, you'd probably strike a good deal.