This is not an estimation of you complete communications plan budget. That said, you should budget for evaluation within your communications plan. The authors advise that a good rule of thumb is that “the evaluation budget should be at least five to seven percent of the total budget of your communication program.”
You should consider: staff time (evaluating does cost time!), external consultant fees (you might need an expert for certain elements), evaluation techniques (are you using any specialized software of service to measure your results?), and dissemination costs (you should share your evaluation with your colleagues, board, and peers in the industry).
You must spend time and money to evaluate your communications efforts. How else can you improve the effectiveness? How else can you allocate your resources sensibly? How else can you respond to a change in the environment?
Tomorrow, a quick final word on the evaluation process.
(Source: Are We There Yet? A Communications Evaluation Guide)