Not cheap, but I very much like it (and the price per printed page is nearly
unbeatable low): Kyocery mita FS-1800+ (the exact model name seems to depend
on region, http://www.kyoceramita.com). With network interface, parallel and
serial. Can take 500 sheets in a closed tray. Duplex and other gadgets can be
added. PS, PCL6, some other emulations. As usual with PS printers you need
more memory (which you better not buy from the manufacturer).

I connected it directly to my 100baseTX switch. It can talk lpr, but I
prefer the JetDirect method:

--8<- from /etc/printcap --8<--
# Kyocer network printer (JetDirect compatible)
lp|Kyocera FS1800:\
        :lp=9100@printer.duskware.de:sd=/var/spool/output/kyocera:\
        :mx#0:sh:lf=/var/log/lpd-errs:
-->8---->8---->8---->8---->8--

If you are printing lots of (grey scale) graphics the older HP printers
(like 4000TN) are better, their "resolution enhancement" algorithm is
very good. But their useage costs are pretty high.

Martin