Here is a site that sells just the lcd screen for the nook (and other parts). From what I can tell it is pretty simple to put in yourself if you find the directions online. I haven't ordered mine yet so I haven't had a chance to try to put the screen back on. They also give the option for them to install the screen for you.
http://www.portatronics.com/index.php?cat=c258_B-N-nook-color.html