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In the Sigalovada Sutta the Buddha gives the following advice regarding wealth creation
He who acquires his wealth in harmless ways
like to a bee that honey gathers,
riches mount up for him
like ant hill's rapid growth
So the bee gains from the flower and the flower remains as radiant as ever after the bee has visited. The bee doesn't just buzz off leaving the flower an absolute wreck. From that I would suggest that the important point is that during the negotiation neither party is harmed at the end. Negotiation is a part of business and a part of life that many lay followers must engage in but nevertheless it is an activity that should not cause harm.
As an aside, Bhikkhu Basnagoda Rahula's book The Buddha's teaching on Prosperity gives much more of the Buddhas advice on wealth and wealth creation which you may find interesting.