I started looking at field monitors (not ready to buy yet, but just looking for interest's sake), and I ended up very confused. The field monitors I found range from $200 to $6,000+ and none but the top few have native 1080p resolution. What about them justifies their price? Why not just get a native 1080p LCD and an external power source and monitor from there for much less money (obviously not less than the $200 480p models, but much less than the native 1080p models)? Is it a mounting issue, energy source issue, or something else that I am missing entirely?