I haggle over almost everything except this. I usually have a number in mind that I won't go above. My respose to someone who exceeds that number is "Thanks, but that's a bit more than I feel comfortable spending at this time."
The best providers usually respond with a "Thanks, I understand" Ocassionally, a provider offers to lower his rate but this is rare and I certainly have no expectations that will occur. Once I see that he is outside my limits, I move on.