The best way to convince the client on fees you are charging is asking the comparison question.

You must have noticed, your client's favourite way to negotiate on the fees you quote is - “We never imagined it would cost that much, that’s more than we intended to spend.” How do you respond to that? Statistically, the best answer to such traps are asking a comparison question. For example, - You can point to a copy machine or computer and ask, “What’s your annual cost for warranties on this equipment? It’s more than the sum total of this project. Are you really so willing to invest more in preventive maintenance than you are in human development?” (Of course, you should make whatever case it is that benefits your project.) You should have done some homework, and worked out these comparisons in advance And you can raise any comparison question like—you can use ruined postage, cafeteria subsidies, carpet cleaning, all sorts of things. It works wonderfully for putting your fees into perspective. In addition to above discoveries here’re a few more actions you should scribe in your work constitution.