The dealer I went through, he had the prices all openly displayed, on a marker board in the lobby, and on his website, and that is the price. Maybe you can get a small discount on the 3rd function Labor install, but the tractor, and the kit are what they are.
He also is kinda directly competing against a very similar dealer about 1h30m away, and they are both virtually identical on prices.
Trade-in, yes, you can see what they will give you, but used tractors, he's gonna want to make a profit off of, and there probably is very little wiggle, maybe 3-5%. Used machines often don't move quickly, and it costs them money to sit there, so...