Customers will argue about the cost of something when they are not convinced of the value of the product. If you have issues with customers claiming your good or service costs too much then you need to either better explain the value or add more to it to increase the perceived value.
Music Credit:
“Relaxing Piano Music” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0 License
http://creativecommons.org/licenses/by/3.0/