Of course the main cost is going to be the installation. It is difficult to put a cost on this as every room will be different, depending on the size, the existing plumbing work and the products chosen. A safe estimate would be anywhere upwards of around £3,000.It might be easier to think in terms of the EXTRA cost over and above a standard shower installation.t is difficult to put a cost on this as every room will be different, depending on the size, the existing plumbing work and the products chosen. A safe estimate would be anywhere upwards of around £3,000. It might be easier to think in terms of the EXTRA cost over and above a standard shower installation.