Migelis, I guess that depends on where you live and how long do you plan to own the car. If you live in Toronto and plan to drive the car for longer than the original rust and perforation warranty, $600 is a reasonable insurance to me. However, I won't even think about it if I live in Vancouver.
In the past, I think extended warranties are just ways for sales people to rip you off until yesterday. My friend's Acura EL had his driver's side window "fell off" in a sudden (it slipped right into the bottom as the window was fully opened). He took it to the dealer and is charged with $590 to replace the regulator module plus labour. He left the shop with $700+ short in his wallet and painful tears.

Of course, it may be partially caused by his bad habit of forcing open frozen windows during the winter, but bad things happen to good people. BTW, his car's warranty expired less than 6 months when the regulator broke. I would consider extending warranties if I plan to run the vehicle longer than the standard warranty period, just for the peace of mind, and an insurance against unexpected repairs.
My 2 cents.