Networking in the business environment is basically 2 types, wired and wireless. That is just the infrastructure. The big question is how is that network managed?
In a basic network, the management is done by a router. These range in price from $39 on up and depending on your requirements, a router may be all you need. A commercial grade firewall is recommended for any business, not only to keep you safe and secure but also to efficiently manage your network traffic. We have seen impressive performance increases by simply upgrading from a typical router to a commercial firewall.
Taking this one step further is an on-premise active directory/domain controller (server). An AD/DC is the most flexible network controller on the market.