I used to not care about fashion. I would just wear whatever was in the wardrobe, and some of what I wore was not pleasant. My friend gave me some constructive criticism and persuaded me to buy some expensive fashionable clothing. I purchased jeans for $200 and shirts for $150. I noticed that many people seemed to treat me with more respect and complimented me on my looks. However, I did some experimentation. I went to Target and purchased $25 jeans and $30 shirts and found that people still seemed to react positively and gave compliments. And looking in the mirror, I do find that the cheap clothes do look good.
So the main lesson from all this is that, yes, people are superficial and will judge you based on your appearance, but throwing more and more money into fashion has diminishing returns. Your average person can tell if you are wearing 10-year-old rags, but if you get cheap clothes that match the latest fashion fads, most people are satisfied. Only fashion-obsessed people will judge you negatively, but shelling out hundreds of dollars on an item of clothing just to pander to these people, in my opinion, fails the cost-benefit test.
When keep up with modern fashion, I tend to just copy what the average person is wearing and I tend to go for the cheapest of whatever it is I am looking for. As always, I believe it is best to do a Google search of something before you buy it so you don't get ripped off.