Milk Powder

With the recent increases in all sort of things, milk powder has also increases. Good for those of us who are breastfeeding, we saved quite a lot on milk powder. But there will be a time when breastfeding stop and we need to buy milk powder.
I breastfed Qi Ning till she was about 20months then I swiatch her to formula as I was few month into pregnancy. I am still breastfeeding Qi Yu who's gonna be 20mths soon and I am thinking of weaning her off my breast. I am tired of expressing milk when at work, mummy is getting lazy. So I was browsing through the prices of different brands of milk powder and talking to different mummy about the type of milk powder they give to their kids. Many try to give the best as claim by the advertiser. Those with all the DHA, AHA lah whatever knot being added to the formula so that the child will be cleverer by taking that formula. When I looked at the prices different between those which supposed to make the child cleverer, it is almost 3x more expensive.
For Qi Ning, when I wean her off my breast, I was fortunate to have the formula supplied to me via my SIL. So I didn't mind whatever brand as it was one of those that claim to have all the important ingredients to make the child cleverer. Later when the supply discontinue I just buy for her whatever that is cheapest on the supermarket shell. Sometime is Dumex, sometime is DutchLady.
Now that I am thinking of weaning Qi Yu, I am thinking of giving her the same milk powder that I give to Qi Ning. But then there is this nagging thought of if I have given my children the best in their growing up years in term of the kind of formula milk that I choose? I think the advertisers is feeding on this kind of fear that parents might have.
So shall I just give them the cheaper version of the milk powder or should I go for the branded milk powder which is 3x more expensive? Will they will less developed mentally just because i didn't buy them the 3x more expensive milk powder? Hopefully not! Looking at my girls at the moment they are growing up very well and are achieving their developmental milestones spot on! But being a mum, the nagging fear is still there, what if I miss giving my girls the best nutritions (aka milk powder) that they need to help their brain to develop in the early year! But I can rest a bit because I breastfed both of them for as long as I can!