There is also who is fronting the money to have the rig at the dealer. Is it the builder (which he has to build into his cost) or the dealer (which he has to build into his cost).
Which is why you may be able to get a better deal on a custom order, since there is no capital cost for the rig sitting on the lot, waiting to be bought.
2008 F350SD V10 with an 2012 Arctic Fox 29-5E
When someone tells you to buy the same rig they own, listen, they might be right. When they tell you to buy a different rig then they own, really pay attention, they probably know something you don't.