@ bomboclat,
there are two types of ballasts available...kayole and mlolongo types...
the best quality is the mlolongo type which on average approaches the ideally recommended size of 3/4 inch (19mm) and is more expensive...
the kayole is of poor quality and not very good for floor slabs...it is normally cheaper...
the businessmen crooks will normally deliver the kayole ballast at the price of mlolongo type...
the mlolongo ballast goes for 21k for areas around kasarani, mwiki, githurai 44 and 45, kahawa west, thome and garden estate.
not very sure about the timber as of this year...
...besides, the presence of a safe alone does not signify that there is money inside...