u/Excellent-Slip844

I'm a student and I genuinely cannot afford $40 serums. My entire monthly skincare budget is maybe $30-40 total. But every time I see routines posted here they're full of $50+ products from Drunk Elephant or Paula's Choice or whatever. I've been using mostly CeraVe and The Ordinary because they're affordable but I don't know if what I picked is actually the right stuff for my skin or if I just grabbed what was cheap and popular. Like did I pick the right The Ordinary serums for MY concerns or did I just buy what everyone else on reddit uses? How do you build a routine on a budget that's actually personalized to your skin instead of just whatever's cheapest?