Although not required, ROW PD may find it helpful to develop data files of all recent real property sales in or near the subject project before pre-appraisal contact or appraising begins. Such files need not be elaborate but should indicate the location and date of sale so during appraisal review it may be determined that the appraiser considered adequate sales. In addition, accumulate information regarding building costs, fencing costs, etc. for the area of each project under development.