How do you explain to your kids why they can’t have branded clothes

So I personally wear all natural fibres myself. So do my kids, as I still shop for them. I’m not at that stage yet, but my oldest is wearing kids size 8 now. We are slowly creeping into the branded clothes era that most kids go through in pre-teens and teen, mostly influenced by what they see their friends wearing. Just wondering should I give in or should I stay firm?

I understand wanting to fit in but I just don’t see why anyone should spend $80 or $100 on Lululemon or Nike when it’s made with garbage fibres…