I had home inspection done for short sale house built in 2000. The inspector find the water pressure is too high (water regulator at 150+). But water inside house (kitchen, bathroom) does not have high enough pressure. What's the problem? Is easy to fix? How much may cost to fix this issue?

Thank you advance for answering my question!

Depends, what part of the country are you in and what is the source of the water, municipal or well. In some areas sediments especially lime, very prevalent in the midwest, especially with well water.