The NADA is not a price list, it is a "guide". Every dealer has their own pricing model and what they work with in profits. The only amount anything is worth when selling or trading is what someone is willing to pay. If you don't like what the offer is don't complete the transaction and find another buyer.
Selling yourself will always get you more but you have to do the leg work to make the sale. When you trade, the dealer has to do the same plus.
You have to decide what you are willing to pay for the whole deal. What someone puts on the individual lines is unimportant, except for sales tax calculations, all that matters is the bottom line.