@daffy
First thing you should ask is the actuations. Next check physical condition of the body. Look for scratches, cracks, rubber pealing, etc. Now shoot with the camera and see that all buttons are functioning. See the quality of the photos (no dust spots, hot pixels, etc.).
Hope that...
Im in the same boat as you bro. I sold my D80 last week and i'm teetering on getting a used D300 but all signs point to a D90 and D300s replacements this year. I would wait if I were you. It sucks not being able to shoot for now but I'll probably be kicking myself if I got a used D300 now and...