The rates for that location are in the range of 30K/Sqm.
You definitely will not get quality work at 18K/Sqm
About the stone finish, that will be dictated by your tastes. If you want rustic, get good hands to do your stone dressing!

is it flyover, magumu or ihindu - get materials from those sides, very cheap - you can get a guy to dress the stones at around 10 bob.
been comparing notes with a friend who is putting up a house those sides and he literally gets his materials (stones na sand) at half the price I get mine huko ruai, shida ni cement prices are relatively higher so he prefers to buy from town and transport huko

@nakujua, seems you are a fellow villager, ni Ruai wapi? Labda nakujua

@coolbull, @nakujua - I am planning to build a mansionette new KBC area, looking for construction materials. What would you advise for
- machine cut
- chumas
- cement
- kokoto/Balast.

Thanks

for machine cut, my fundi used to get them from juja, most of the transport guys can get them for you - I think thats the best place to get them, the ones sold on the roadsides especially hapo ruai and along kangundo road are of very low quality, I would avoid those at all costs.

Chumas - there are many hardwares around, I used to go round asking for the best price and the one that offered me the best I got from them. I had been told about kariobangi, but that was too far and the transport and uncertainty made me ignore that avenue.

Cement - I was lucky enough there was a small hardware near my site, they were slightly expensive - but the good thing is that I could get the same on credit and even if the fundis run out of the same when I was not around it was easier to organize.
my 2 cents get a hardware near the site and talk to the owner, it would be better if they can deliver - it helps especially if you happen to be low on cash.

Balast is readily available those sides, the same as sand - the tricky part is that different qualities are needed at different stages - my advice on that would be before starting familiarize yourself with the different qualities and if possible always be present during unloading.

That kbc area is really opening up and looks like a very decent place. All the best, and remember a good fundi will save you lots of stress.