Digital BW, The Print

If you are honestly only concerned about B&W printing then you certainly don't need a wide gamut display.  That will save you a bunch of money right from the get go.

Next, make sure you've got a PVA or IPS panel.  And make sure you are buying a model that is known to not switch panel types.  This is a frequent problem, make the first few batches with nice IPS panels and ship those to reviewers.  Then keep the same model number but switch to a crappy MVA panel instead.  Dell and HP are frequent offenders.  Unfortunately you really need to do your homework or pay a bit more for something like a NEC if you want to know 100% what you are getting.

What size is a big question.

Finally, definitely find user reviews on the monitor for the above mentioned reason - monitor companies make sure only the best go to the reviewers for the first bit of production.  After that - well it is hard to say what will happen.  Dell has a monitor out there now that they advertise as using a specific panel technology and meeting a specific delta E.  Problem is they only test it in the center of the panel and people are getting truly horrific magenta to green shifts in tone from one edge to the other.  Dell's response is, "It is within our spec, since we only measure the center, so kindly go pound sand".

This is the best resource I know of:

http://forums.anandtech.com/showthread.php?t=39226

Again, the major point is that the "awesome" deals to sometimes be had from Dell, HP and the like are sometimes fraught with peril.

Good luck!  My experience is researching and purchasing a monitor sucks :(.

Ken