Keep in mind that most things are negotiable at the dealership, even things you might not expect like parts and extended warranties. OF COURSE they aren't going to tell you that. If you are on this forum, you were most likely well prepared for negotiating the price of your truck. You should also be prepared for dealing with the financial staff, and have printed quotes from Zeigler and Clay Robbins at the ready. You might be surprised that they suddenly will offer competitive pricing when shown some other warranty offers. Probably won't work on a third part warranty, and may differ depending on other parts of your deal, the time of month, the cycle of the moon, etc.
Worth a try, and little effort on your part.