If you're buying a large software license today — and I bet this holds true for at least some houses, cars, other "high-pressure sales situations" too — the vendor definitely won't think of the negotiation as adversarial.
In an unending game of the prisoner's dilemma, either you all win or you all lose.
I wouldn't use the term adversarial for this. Ideally in a house transaction, the main thing is that both parties want the deal to happen - the seller wants the money and the buyer wants the house. They very much have the same goal of getting the deal executed.
Now obviously all other things being equal, I'd rather pay less money (or charge more money)
But in most cases, neither the seller nor the buyer operating in good faith will really try to squeeze the other because losing a multi-hundred-thousand (or even million+) deal by being too anal about $1000 is in neither one's interest.
If a seller got very "adversarial" most buyers would say "fuck you, I'll keep looking."
In an unending game of the prisoner's dilemma, either you all win or you all lose.