I've got 25 years' experience in creating scripts for call centers and other phone applications (such as automated messaging systems), and am VERY good at helping the speakers get their voice inflections right.
The actual cost for my work will depend on the number of different messages that you need to be created for your agents, and how much training the agents will require to learn to follow the script, handle questions and objections, etc.
So while I really can't quote you a definite price yet for this job, I can assure you that my script will be extremely satisfactory to you, and that your agents will be able to do a very good job of using the script to perform the activities that you need them to accomplish!
If you care to discuss this further, you can reach me at johnvin999(at)yahoo(dot)com, or at 1613XX456XX6255.