I'll just add my thoughts since I just went through this. First it's very easy to see their price plans on their main page, they don't hide or confuse them. You click on the TV tab, there are 3 and 4 year plans. You select the price you paid for it minus tax, then click on "get plan" to see the price. For a plasma like my VT50 55", which I got on sale for $1499.99, the price for a 4 year plan is quoted as $169.99, sales tax is added on checkout.
If you want to open up a bunch of google search windows, after searching on "square trade warranty coupons", you can try and find a working code for a discount. You have to be quick, as I had no idea people seem to be buying these warranties like hot cakes. I had nothing else to do for hours while sitting at my computer and kept inputting discount codes from various sites. Everyone of them showed "used" after I entered them, but I guess I got lucky at one point and a coupon code went through, saving me another $30.00.
The Best Buy plans were a lot more, and from what I read all over the net, not worth it, though some had good luck. I choose Square Trade, since that is is the company Panasonic links to on their own site, as I assume they don't want to be bothered with extended warranties. Seems you'll read good and bad stories for all of these companies. I only bought the plan as this is a heavy TV and if I ever need service, they are supposed to come to your home. And, YES, like almost any extended warranty, from Apple and other majors, you always have to minus the 1 year warranty you get from the manufacture. So my 4 year plan is in reality 3 extended years, for $140.00, in my case. I felt it was worth it, hopefully I'll never have to use it.