It depends on if you'd like a good one, Samsung or a not great one, Vizio?
People think HD is HD and a flat screen is a flat screen. Go look at Bestbuy and you'll see a huge difference in picture quality.
LED, not worth it to me. 3d, when will they stop this shit. Plasma, bet value, just be weary of burn in, if gaming.
Last, the "thin" selling point on tvs...ridiculous. Unless, you store your components (cable box, xbox, etc) in another room, you'll have a set up @18" deep, regardless of whether you flat mount your screen or if it's .0004" deep.