What you can do is buy two brands of diapers. During the morning, when he's more concious and the probability of wetting his diaper is higher, it might be better to buy a really cheap diaper. At 65 pesos, we're able to buy cheap diaper (for 25 pcs) and were able to save a few peso. We figured out that since we're changing diaper frequently anyway, why use branded ones? Of course, children can be irritable to certain types of diapers, especially if you leave them wet. But babies usually only gets exposed during the night, which made us resort to using more expensive and branded diapers. For branded diapers, it would cost around 230 pesos for 22 pcs.
Now this might not be applicable to all parents. You'll have to observe your child's pee and poop habits.
I hope that helps and please stay tuned for more future money saving tips.