In setting the rates to be charged for the service, use, or benefits derived from such facility or utility, or in determining the cost of the planning, acquisition, construction, reconstruction, development, improvement, extension, repair, maintenance, or operation thereof the legislative body of the city or town may include all costs and estimated costs of the issuance of said bonds, all engineering, inspection, fiscal and legal expense and interest which it is estimated will accrue during the construction period and for such period of time thereafter deemed by the legislative body to be necessary or desirable on money borrowed, or which it is estimated will be borrowed in connection therewith.