Sandstone wall cladding on Blueboard

Hi there

I am in the process of extending a couple of rooms. A builder friend of mine is helping me out (or the other way round).

The plan at this stage is to use blueboard and then a 'stuck on' sandstone-type wall cladding.

Could someone enlighten me more on this subject and whether it is the most cost-effective way to do it. Is this just a 'stuck-on' tile-like material? How much roughly.

By the way, the existing wall is brick (sandstone, yellowy colour), that's why I was thinking of this 'stuck-on' wall? The wall is 11m long, about 3m hight, 5.8m on both side.

By the way, the frame and roof are up.

Thanks heaps.