Maintenance cost? Well, if my GPU takes 50 W less juice a hour, and when i play 10 hours a day (kinda possible, im sometimes that crazy). Its already half of a kW a day, means 10 cent in my country. When i do it 1 week in a row its 70 cents. 2.80 Euro a month, 33.60 Euro a year... although not even a hardcore WoW player would play 10 hours a day... well some does... some does but way to rare. Still, what i want to say is that it indeed will add up. Under worst case condition, some got 2x 480 GTX (we have users like that, who happily bought it because performance is all they care about). Then they have +200 W, and in 10 h 2 kW = 40 cent a day...over 100 Euro a year, in term they are a hardcore player...So theyr GPU can indeed cost more than the initial cost. Thats just as far as cost is concerned (not being "green"), i know that most US apparently enjoy to have theyr country full of nuclear reactors and some might enjoy to have one of them right at theyr home (and personally owned).
Well, i mean many of those people are happy for getting those leeeeech GPUs almost for free and are unable to see the higher maintenance cost, or apparently its not visible to them.
I have 170 $ electricity cost a month... and i even have LED bulbs installed at most spots already... i do care that "cost". But i know, in US electricity is cheap and produced by 130 nuclear (including new ones) reactors (but thats just a temporary cost drop, as soon as out of material or explosion happens, cost will increase).
But for me GFLOP/W and price/dollar ratio
including electricity bill (thats part of the ratio), is important, for most OCers not. But it doesnt mean that OC can not be "green", a OC 7850 or a IB CPU is still extremely efficient, even at OC. Another concern is the noise of the fan, because my system is to small for water cooling, a cool running GPU is important!
About how long your PC or TV will last, thats a matter of luck because nowadays so much cheap stuff been build who can instantly go boom all of a sudden. Some stuff such as my 7850 is defective from day 1. But that can happen to any other hardware, some SSDs/HDDs did only last 1 min. The hardware i trust the most is "RAM", they truly last almost forever. 
