It's a nice drone in a perfect condition. make an offer. 
Hello, I would like to pay $400. Would that work for you?
nope. That's way too low, man. At most, i could probably knock off a hundred off the price. so 650. But really that's the most I can do
Are there other offers currently? I have seen a similar product available for $500, but it's farther away so I wanted to make a deal
There are a plenty of other drones for that price. some will be new too, but they won't be DJI phatom 4. You're paying for quality here my friend. 
$500 is the highest I can go
tell you what. 600, and you have your drone. a perfect condition. phantom 4.  deal?
Unfortunately I do not have enough available for that, I could round up some cash to hit $535?
I can't do that. Sorry. 600 really is the lowest. Maybe this drone isn't for you
Yeah I will look elsewhere, thanks for your time