If it's just a B & W laser you want, look for a HP 4000 or 4050. The son of the 4 and 4+. The last of the 'good' HP lasers. No longer in production, but refurbs can be bought reasonably priced. Add a network card (the 4000N & 4050N come supplied with one) and away you go.
Printer Data Sheet - HP LaserJet 4000 Series