I hope you mean corrugated iron sheets for walls?
If so, not much savings will be realized cos iron sheets are damn expensive nowadays. May be you can try getting rejects mabati from Devki in Ruiru. relatively cheap and would work perfectly for walls.

Just thot of posting what I went thro when doing the electrical wiring of my house.

Got a couple of electricians who came highly recomended. Took both to the site and asked them what they would need to wire up the place and follow up with KPLC to get the electricity connected.

One electrician told me to buy about 60 rolls of cables of different sizes average cost of 3000/- a roll. I wrote him off. The next one told me to 30Rolls of EA Cables and seemed to what he was talking about.

When we went to buy the wire he showed me a kajoint in Nyamakima where EA Cables wires are cheaper. Just as I was about to pay I decided to look a little closer. Some rolls had the wrapping writen EA Cables in Green and others writen the same in black. I then thought there is no way a company can do this type of packaging in different colours.

Anyway the cable I was buying were fake and unbranded even if writen 'East African Cables'. Thank goodness for google as i googled up a distributor and found one on the next block and were actually the same price as the ones I would have got.

Anyway hope ull get your wiring from a trusted source. Most contractors will just take you to where they have pre arranged for a cut.

My electrician had also recommended some place in Nyamakima for 'cheaper EA cables' but I refused and instead took him to the East Africa Cables factory in Industrial area where we got the wires.

@BensonNzuki the above might help.

Benson Nzuki - 670.00 simba cement if you are buying large quantities.