[pfSense Support] seperation of network

[Jason]

Hi,       I need to let some of our guests to use our broadband, but I'm concerned about security. Can I force them to use a different subnet other than my Lan? It seems that vlan is doing such a function, but buying an expensive switch is not an option for me. What else can I try? Can I add another cheap NIC and another cheap hub for the job? Thanks for help.   Jason