Fair enough. In any negotiating session, there is a point of diminishing return and wasting time going further.
You get 75-90% of what you want, it should be closed.
I do understand the point about nickel and diming. It often happened to me as well and was extremely irritating.
>>It often happened to me as well and was extremely irritating.<<
You sort of see it coming after you reach a certain experience level. Depending on the customer you can do one of two things when you start seeing it in a customer, you can set the rules and expectations right up front and pretty effectively mitigate it, or you can hand the customer to someone else, either overtly or covertly (through causing them, through whatever means you choose, to want to work with someone else).
Life’s too short to work with crappy, arrogant, full-of-themselves customers.