Best camera in your price bracket in my estimation is the Nikon D5100. For landscape lighting photography, an important aspect is the dynamic range of the camera. I agree with James, and Tim, a good piece of glass can set you back a bit...but even a good piece of glass on a camera that doesn't have a good dynamic range will not give you good results. Check out this website for comparisons on camera sensors;
Look for high low light/ISO ratings, and good dynamic range. This should help point you in the right direction.
Nikon has lot's of good lenses that you can upgrade into, if you start with a good sensor for your application.
If you are looking to for something more compact, the Sony NEX mirrorless cameras have the best DR in the compact line up. You could get into a NEX 5R for about $600. Again, lots of good lenses to upgrade into.
Hope this helps!