If you have to ask you shouldn't be advising anyone.........itblock is 0.4 x 0.2 = 0.08>>1/.08 =12.5 per sqm in your case as you are building cavity walls..times 2 so 25 blocks at 6.5 baht -162 Baht 5 satang
Grade B Q-con 0.6 x 0.2 = 0.12>> 1/.12= 8.333 per sqm @ 14 baht = 116.66 but they charge VAT so 124 Baht 83 satang per sqm
Cement or glue is much the same cost due to the small quantity needed for q-con but the labor charges will be much much more on itblock