[Quickurt]

I think this is a very simple decision tree.
If you can buy the car you want and be able to say damn it and write the check to repair/replace the stuff that go wrong, don't waste the possible loss of buying a warranty and then not needing it.
If the above sentence (run on as it may be!) will keep you from sleeping at night, buy the warranty or don't buy the car.
The worse possible scenario is one similar to what addictionracing went through, where he had the choice to spend more than he thought it was worth for a new engine, put in what he thought would be another bomb used engine or dump the car for what it was worth with no engine.