Not from Nigeria but my two cents:
I am of the opinion that every country should have minimum wage regulation since this stops the abuse of workers, because in some countries, employers pay less to the workers, and workers often tend to not have any idea either what should be the ideal wage they should be getting.
You mention that employers might employ less people but the ones who work there will getting wages they deserve, which is big positive, and regarding prices — I can speak for myself, I would not want cheap prices on exploitation of somebody else.