As others have already replied, LCDs use a lot less power. But if you want a flat screen for a decent price with an excellent picture, Plasma is still the way to go (as your research told you obviously). And Plasmas are getting better / more energy efficient (just not as good as LCDs).
I did the same thing you did...spent weeks doing my research and looking at TVs in stores, and walk away with a Plasma. Because picture quality was more important than my electric bill going up by $1 a month. Granted my Plasma is only 42" and is rated at 286W (with people online claiming they've measured an average of only 200W used).