Here’s an excellent paragraph from my Negotation text:
If we negotiate because we value things differently, it is in the bargaining phase that we focus on the differing valuations. Nothing, absolutely nothing, should be given away, no matter how little it is worth to you. The paradox of bargaining is that those things that are worth little, or less, to you in themselves, could be worth a great deal to you in the bargaining phase if they are worth more to the other negotiators. The form of the bargain is the conditional offer, and the tradables available to the negotiators are the potential content of the conditional offers.
Great paragraph huh?