first look for the real landowners with huge tracts of land and ask them to sub let it to you ,e.g in kawangware,waithaka,kinoo,uthiru etc,monthly let of 100 by 100 is around 30,000 ksh .look for a good site near a main road.erect semi permanent rooms using mabatis,a 12 by 12 room can cost you around 45000,a 100 by 100 can hold around 60 rooms which you will let for 2500 to 3000 per month.fanyeni hesabu,if you're in a sacco they will be lending you money to construct,if you are creative enough you can even jenga za ghorofa using mabati.