Well, agreeing with your parents, especially when they claim something is a rip-off is a pretty incredible and rare incident. We keep on asking for more stuff and more money for new stuff and our parents try to balance the scales. A family house or flat is not easy or cheap to maintain, feeding a family isn't either. So we should be more than understanding when they can't do everything we would like them to do for us.
However, there are such obvious rip-offs that even we can't help but agree with our parents.
Don't waste your money on stupid stuff.