if they can offer the VT30 for 39K, I'd say an equitable price for the ST30 should be 20K.
. Then I would think about the ST30.
My ACTUAL consumption on my 50V2 purchased in March 2010 is 30% of nameplate rating. My wife who uses a 2010 42V20 still does not know the effect of that TV on her monthly bill. Panasonic Japan claims 25% (of the backplate rating) for the 2011 VT model and even lower for the 2012 models. Boss Vic says it's 50% on his locally available plasmas. Take your pick. Perhaps the ST is not as efficient as in higher than 30% or 50%, I dont know - but then it's nameplate rating should be lower than the VT anyways. So malamang mas makakatipid ka ng KONTI sa ST than a VT - as in a few kWH per month.
Compared sa LEDs? If every Filipino saves 100 Pesos a month, then the country would have extra 10B Pesos in a month. Wow cool! But to you as an individual, how big is 100 pesos a month, or 200? Problema, if you like your plasma TV too much, you'd use the aircon longer and the power hungry AVR and subs - that will increase your electric bill - but can you blame the TV?
And dont forget, an equal grade LED will cost you a lot more than the VT30 which is quite likely un-recoupable during the entire usable lifespan of your HDTV. So saan ka nakatipid in the end?