What sorts of things are you looking to buy?
I watch a few makeup artists on YouTube, and some of them have done drug store hauls and explained how some drugstore brands were still quite good on them in terms of the look and affect it had on their skin. But obviously the more expensive brands are better as they don't usually carry the risk of damaging your skin or looking horrible. I don't wear that much makeup, I only wear foundation from Mac. 1. Because drug store makeup brands don't really cater to black people. 2. The matchmaster foundation I have is so amazing it's the perfect match to my skin tone. 3. It lasts for months. I occasionally wear lipsticks, but I buy from brands like Rimmel and L'Oreal, and have had no problems with them.
If what you're buying is expensive but lasts very long then I guess it's worth it. That's why I have no problem buying my foundation from Mac because I know it's worth the price.