@charlesgava_256 For the case of plastering, the hollow bricks have two fair faces compared to clay bricks that will have one fair face. The mortar for the plaster will always be less for the blocks.
The costs can be more less cheap provided u decide to make your own blocks.
@charlesgava_256 Here is the breakdown for a square meter of walling.
1. 1 burnt clay bricks header bond (230*150*75mm) - 57 bricks
1.2 hollow bricks (400*200*200mm) - 10.5 bricks
2.1 mortar for clay bricks - 26kg of cement
2.2 mortar for hollow bricks - 13kg of cement