Before getting too excited about negotiated extras, realize that most things that they give you will be of the lowest quality. I'm talking about sewer hoses, pressure regulators, batteries, etc. Many of these things you will end up replacing before long, so don't think of them as getting something. Even the battery they give you won't be the best.
I'm not saying don't do it, but just consider what you are getting, and don't get too excited. My dealer offered me 50% off in the accessories store on the day of pickup as well as the usual box of goodies I probably won't use because I already had better stuff from my last trailer.
2016 Jayco Eagle HT 29.5BHDS (ordered 12/30/15, delivered 3/8/16)
2015 F-350 crew cab, short bed, 6.7L PSD, Pullrite Superglide 3300 hitch