I think you've gotten some good advice so far. The question of extended warranties doesn't have a "right" answer. Some say it's a fool's bet because the warranty company has to make money so why not just cut them out of the equation and put that money into an account and pay your maintenance out of that. Some, like me, bought one because they were new to RVing... had no idea what they were doing... and didn't want to be hit with a big surprise repair bill. For us it provides peace of mind. Some... do neither of the above and just take their chances or don't worry about unplanned expenses.
But, I do think dealers charge more for them and the price is very negotiable. Just as an aside, if I understand their policy correctly, the Winnie factory in Iowa will gladly service your coach and honor your extended warranty but I think only if you bought the wty from one of their dealers.
Best of luck...
Rick