Well I guess some are better negotiators than others. I do this (negotiate) for a living but one thing you are mistaken on if you think that it is desirable -- dealers like "cash" buyers -- they do not. All thing being equal buying one on the ground is cheaper---the store in question needs to get it off of the floor plan. Have bought 31 new cars and trucks in my life and have never had to order one. That includes MB AMG's and my Shelby GT500 which I got X-plan plus the rebates lol.
I paid 215 dollars over invoice for my Raptor and if I want another -- the same deal will apply---discussed it with the Owner a couple of months ago. Buying cars is no big deal you just have to be willing to do the due diligence and be smart. Buy hard to get vehicles frequently and always close to invoice. Bought a Audi TTS for my wife earlier this year---very limited production with not many in the country at one time got it through my companies discount program with them which is just about invoice. The first 2 dealers one in Houston had one and the other in Atlanta said no way msrp only. Did the research and got it shipped from Houston to here (that cost me 250) and the dealer here had another desirable vehicle that the folks in Houston were willing to trade (had a buyer and called the dealer here the day before) for so it worked out. Sometimes takes some legwork, some phone calls and a lot of emails!!
Tried to post this yesterday several times but could not get into the site because of the "attack" problem with the server..