I am deciding to buy a kvm of 4 ports WITH usb on my keyboard n mouse, which one is the better kvm switch and how much?, I have 3 pc are need to be one monitor.

Gefen if you have the money. I am currently using a aten cs1782 which is awesome because it has audio and usb switching and is DVI they have the same model in 4 port model as well. Kind of wishing I brought the dual head dual dvi version though

audio switching = a must