I bought a Quality Guard Supreme warranty when I bought my VX in December 2004 for $2k, which covered me for 4 years and 50k miles from that point on. Quality Guard is part of Nissan, I believe (I bought the VX from an Infiniti dealer), and it has paid for itself already by covering over $2700 in repairs.

They can be a little picky about what they will cover and what they won't. For example, they will only cover repairs of non-wear-and-tear items, and only if a part is broken. A 1.5 hour labor charge ($115) to figure out why my cabin light kept coming on (the passenger door latch was loose and allowed the door to wiggle open enough to trigger the light) was not covered, but a rebuild of my differential for one worn bearing (~$1800) was covered. But once the adjustor came to see the differential repair, he disallowed the replacement of some valve because it wasn't actually broken, it was just clogged.

Overall I am satisfied with it, though. When it comes to the VX, any repair can be very costly in terms of rare parts and dealer labor, and two significant repairs can easily bump over the price of the policy.

Good luck!