"I don't care if it's a '4 Panel End of Day 15/16" Onionskin.' It's still just a marble, and I won’t give you a hundred bucks for it. 75 bucks, my final offer, take it or leave it."
"Look, it’s worth every nickel, but I need the cash, so I’ll throw in this china-grade hand painted clay marble from the 1800s. In fact I’ll give you three of them, all different, for the next five minutes or forget it."
This little negotiation started off as a traditional negotiation, "position based". Many negotiations never get more sophisticated, and may end in no deal. If one party switches to a “needs-based” bargaining model, things can go forward.
That can happen by one asking the other what his or her real needs are. Almost every deal is really based on multiple dimensions—if nothing else, the terms of payment. A buyer, like this one, may need quick cash, but willing to throw in something extra "to boot." On the other hand, a buyer may need time to complete payment, and be willing to come up in price to get the time.
Negotiation 101: needs-based negotiation seeks to discover this information to smooth the way to a deal. For more, see my article at A Better Way to Negotiate .