I agree with what most people have posted for the most part.

Spend- foundations and concealers. It is just better to spend more for color match staying power and avoiding things like oxidation and transfer. At least for me. Also setting powder I know you see dupes and I have tried them but just get the real thing you will thank yourself.

Things I go either way on. Eye shadows- I tend to stay mid range or higher with eye shadow. I can pretty much work with anything and make a look. Would I love to always use high end shadows sure but I live in the real world and I sometime want to play around so I buy drug store stuff. Eyeliner- I'm finding now I likes spend a bit more especially on liquid liner. I am just not getting the staying power or performance out the applicators with some of the drug store liquid eyeliners I was using. Lipsticks- matte lippies I'm not getting drug store any more I have no luck. But other formulas I'm pretty flexible. Primers- it really depends on home my foundation works with it. Skincare- my cleaner intend to splurge but I use glow tonic for toner and my face and eye cream is olay; my nan swears by it and she doesn't look any of her 80 years so I'm going to trust her.

Save- mascaras- my eyes are so sensitive so I don't mess around with them for to long. If my eyes start to feel itchy and it's not allergies I trash them. Lip treatments- people use all kinds of crazy lip stuff. Just like my eyes are sensitive so are my lips. My lips break out in a rash all the time I am allergic to something and I don't really know what so I only use blistex medicated lip balm. And the prescription cream my doctor gave me.