http://www.amazon.com/Samsung-ML-251...ref=pd_sim_e_2
I've been using a slightly different model of this laser printer for 3 years and it has worked great. The toner cartridges are ~$35 for an off brand or $80 for the samsung. I'm using an off brand currently and have had no problems. Both will give you 3k pages.
Networking is a great feature if you have multiple computers that may need printer support.
For used go for an HP laserjet series. My parents have an HP laserjet 4 that has the old LPT or whatever printer cable they bought it in '93 and its still going strong.