Cisco Catalyst 2950-24 24-Port Ethernet Switch (c2950-24)

Cisco switches are probably the best in the world. Industry standard and tons of them around, so you can get an old model for a fraction of the original price.
Novices will love these switches because you fit and forget, experts will love them because you can play with and alter almost any setting for each port.
If you rely on your network for any kind of business service, don't buy anything else, stick with second hand Cisco as it's ten times better than almost anything else purchased new!