I need some advice on a good kvm switch. Must be a 4 port with usb / vga / audio. Also, it must be able to work with just one computer hooked up to it (I guess it must be powered) and I can scale up the other 3 computers as needed. My budget must not exceed $200 but cheaper is always better. This is for my repair shop. I almost always need to work on at least 2 systems along with my own. Please help. Thanks!