Survey costs depend on the type of survey and the size of the site. A topographical survey of a small site is a modest fixed fee; a measured building survey, a site suitability assessment with percolation testing, or a full geotechnical site investigation with boreholes are separate exercises with separate costs.
'Site survey' can mean several different things. A topographical survey records levels, boundaries, trees and services and is used as the base for design drawings. A site suitability assessment for a wastewater treatment system, carried out to the EPA Code of Practice, involves trial holes and percolation testing. A geotechnical site investigation examines soil strength and groundwater to inform foundation design.
Cost varies with site area, access, the number of trial holes or boreholes, and whether laboratory testing is required. Getting the right survey early is normally cheaper than redesigning a foundation or drainage strategy later.