The tours are roughly 2,500 Euro for a week, all inclusive. You stay at the fanciest hotels, eat their best food (comparatively speaking), and get to see all the museums, landmarks, DMZ, and so on.
I have been researching this for quite some time, and hope to go next summer.

It should be a once in a lifetime experience!

http://www.koryogroup.com/
http://www.korea-dpr.com/travel.htm