Good Luck!!
So, the cheaper you buy them new, the worse quality, and they'll definitely be made under unethical conditions. The best ways are: 1. Thrifting. Find the ones in your city, and use reviews or areas to find out which ones are bigger, or in more affluent neighbourhoods. You can find designer or just very stylish clothing for cents. Second, would be ebay. People are desperate to sell on that site, and you can find exactly what you want for 5% of the price.
if you don't really want to buy used clothes I would say go to Ross, Marshalls, and other stores like that. The clothes there are pretty cute and they're relatively cheap. I can usually find a pair of jeans there for $12, but at goodwill I can get jeans for $5 and they'll be from hollister or american eagle and not a pair of jeggings from a department store.
Abercrombie, pacsun, hollister
primark
try going to thrift stores and you could diy them I'd you don't quite like them.and forever 21 and target have some cheap and cute clothing if your not into thrift shopping.
I would seriously recommend Plato's closer if you can afford to go there you can buy a garbage bag full of clothes for 100 dollars. If you can't go there try a second hand store like goodwill.
Thrift stores/charity shop try and find small retro-vintage shops they also sell clothes for reasonable prices or you can also ask friends or family if they have any clothes they could kindly give to you it doesn't need to be a perfect size on you because you can also try to customise and remodel them.
Walmart
thrift stores
i go to la and i buy shirts for 3/2 dollars
jeans for 10
and sweaters for 5 dollars
itsa at san pedro rd rode where theres a bunch of boutiques
in dowtown la
at 4 in the morning (no joke)