Should you have someone haggle for you? It depends.
Above all, negotiators help principals stay on good terms, allowing each side to float aggressive positions without commitment. They buy you time to think and make the other side work harder, since there are two (or more) of you to persuade. And if you have shortcomings at the bargaining table, your negotiator can complement your strengths and check your weaknesses.
Conversely, agents, brokers and other professional negotiators take time and cost money. They also often have their own agendas: The commission-based professional is aware that he or she receives nothing if your deal does not close, while those charging an hourly rate might not care. And many business deals are too small to justify the expense.
No matter how powerful a rep is, he or she is working for you, not the other way around. Clear agendas can help keep negotiators on the straight and narrow.
Finally, know when to call off the hounds. When timing is critical, the principals usually come to terms the fastest.
A speaker and attorney in Los Angeles, Marc Diener is author of Deal Power.