I view it instead that I am offering a service. I am well aware of what my service is worth, what my financial needs are and what amount would make me feel satisfied with what I am being paid. So I tell them that number.
I also tell them that the number is only negotiable in the sense of benefit trade-offs. I have built into my "price tag" such things as medical payments, etc. If they can offset some of those from salary to benefits that does not bother me. In the end my needs are met and I am happy.
I refuse to see the relationship with an employer as adversarial. It is a business relationship, I treat it as such and demand they do as well. Otherwise I don't do business with them.