One general principle-- the harder the salespeople push for you to buy
an item, the higher the
profit to them and lousier value to you.

In particular, all those places that push for "extended warranties",
they can often triple their profit just on the warranty part.

And collecting on the warranty can be a real hassle. Not like the
smiling attractive people in the glossy warranty brochure, you'll be
writing and calling and getting put on hold for months if you try to
collect on the warranty.