Depends on the estimate. There are 3 basic types, square foot, unit cost, and detailed. Most “free” estimates are sq ft proposals. Although estimates vary in the purposes for which they are intended and in method that is used to develop them. Detailed Estimates usually cost because of the time involved. However, a detailed estimate can provide a detailed accounting of the expected costs of the material, labor, and sub-contracts. So it may be worth your while to pay for a estimate depending on the project.
Consultations should be free if the contractor or contractors know what to look for in a home or business.As a contractor I dont charge to give an estimate.The first look should just be to see what is it that your wanting to have done.Sometime just because one is a contractor doesnt mean their capable to handle what your need to have done.So yes I would be wary if there asking for a service fee.