I always look at it this way. If I take the added amount per month I would have to pay in order to obtain an extended warranty--let's say $17/mo, just to go with the same number as above--and put that aside each month in a "rainy day" account, even with the abysmally, horridly low interest rates on offer these days, in 3 years I've got a little over $600 saved, in five years over a grand, and I'm well on the way to paying for whatever repairs I'm likely to need. Granted, if I need something truly big, I will still have to dip into other savings, but if I've bought a good vehicle, as I believe I have, and I take care of it, as I surely plan to do, it's unlikely I'll need the extended warranty beyond what I'll have saved. And when I sell or trade the car, if I haven't used the money, well, it's a good start on the next.
Multiplying this idea by all the items for which I receive offers of extended warranties, I can instead be putting aside that money and investing it--and if I put it into a conservative mutual fund, I'll likely get a decent return over time--and coming out well ahead over the years.
I have a brother who is an actuary. He has promised me that if he ever hears of me buying an extended warranty, he will slap me. Of course, he also strongly suggests saving for a rainy day. Got the idea from Ben Franklin, he says.