Don't bother ...
Do you think there's a 1-in-6 or 1-in-4 chance of it failing ? Probably not ... Most TV models have less than a 10% (1-in-10) failure rate in a 3-year time span.
Not to mention that this is a fairly new technology (at least to the mainstream market) that is improving greatly with each passing generation AND the technology is getting cheaper to produce with each passing generation.
So, to answer your question, I think it's stupid to buy a warranty that expensive on a TV that cheap, especially considering you could buy a TV of similar quality for ~$400 next year ...