DOES ANYONE HAVE AN IDEA OF HOW MUCH IT WOULD COST TO HAVE PILING FOUNDATIONS SUNK FOR AN ADJOINING SINGLE STOREY EXTENSION? I ESTIMATE THEY WILL HAVE TO BE SUNK AROUND 2 1/2 TO 4 METRES DEEP. THE SIZE OF THE EXTENSION WILL BE AROUND 30FT BY 8 FT AND WILL NEED PILINGS ALONG THE 2 ENDS AND 1 SIDE.