A short background; I bought a 99 new (31K) and had it 16 years and sold it at 311,000 miles ($12K), great truck, but going deaf!
Since then Ive purchased 5 new F-350 loaded 4X4's (Live in Colorado), for hauling heavy loads.
I have never finalized a deal until the dealer has dropped at least $10K off the price. The dealer has his own "discounts" that they allow on most sales to knowledgeable buyers, but not a lot of people know that the dealer also gets a Kickback from the factory that is not seen in the paperwork. This kickback is up or down depending on how many vehicles the dealer sells. So when the sales guy tells you he can't go any lower because he has to feed his kids, he's not giving you the whole picture.
I never go in and tell the dealer that he must drop 10K off the price or I'm leaving, just shuts them down. I always give the dealer the true impression that I need this truck, that I want this truck, but I still need to replace the roof on my house this year or braces for the kid; giving the dealer a reason (no need to lie, everyone has needs), gives them a reason to work with you.
I'm always more knowledgeable than the sales person. I always reach out to dealers within a 300 mile radius for their input. I always go to Auto-trader, or Truck-trader type web sites and see what the truck I'm purchasing is going for across the county. We've purchased three vehicles from out of state, a Jeep from Florida person, a Jeep from a dealer in Chicago, and a 15 SD DRW in Louisiana from a dealer, all good deals. By the time that research is complete I have two options out of state to finalize a deal, and Then I go to My Dealer, not before. When I enter the dealers showroom I don't let the first sales guy come up to me, I ask for the manager. I tell them I'm purchasing X and would like the most knowledgeable Sales Rep for that vehicle and I'm hoping we can make a deal today. This signals to the dealer that you are a viable purchaser and mean business. I'm always respectful even if the dealer can't get to my known to me sales number.
After the purchasing of the 15 SD, I then purchased a 17 SD, two 19 SD's. and finally landed on the 21 SD that I still have. On the 21 SD my local dealer, who had sold me all but the 15 unit could not meet my sales price so I thanked him and left. I told him I will get home and finalize a deal I have on the table on my computer. I live 30 minutes from home and he knows this, when I was pulling into the drive lane of my ranch he called me and said, "its a deal, come on back, we'll stay open for you". Deal Done.
Remember, the dealer gets his kickbacks from the factory rated by how many vehicles he sells, I believe the dealer sold this at close to his cost to add the truck to his total sales number. I know my sales guy very well and believed him when he made that statement.
It's all about homework and best to you, Rick
PS, On a 90K plus truck I would not buy until the discount is over the 10K number, the higher the MSRP the more room there is to give.