If you're getting a factory warranty it's different than getting an aftermarket "extended warranty" which is really just a service contract.
There are several factors:
1) do you only get work done by someone else, or can the work be done by yourself, thus saving labor costs?
2) are you prepared to pay cash if you don't get the warranty?
3) do you have the discipline to save the money in an emergency fund, even if that's an online savings account like ING Direct? Personally, we have did not purchase the extended warranty on the Trailblazer becuase I did not think the cost (which is negotiable) was worth it over time. I paid cash for the Cavalier and it came with an aftermarket service contract good for like 80k miles, cost me like $25 to transfer it into my name, so that's worth it, even though it only covers so much stuff. Anyhow, we have $100 transferred to an online account just for emergencies, which I've had to use a lot lately, BTW!