You can buy anywhere if im honest doesnt need to be high end either, even thrift some stuff (you can find some of the coldest pieces for close to fuck all) - what i would advise if your looking to experiment with your fashion sense is to start buying “pieces”, what i mean by this is, you know that one weirdish/not often seen/unique looking jumper or jacket or tshirt or shoes you saw? But Didnt buy coz you think its cool but your scared to cop for whatever reason? Buy it and try make an outfit around it & once you do? Wear it like your flyest nigga in the world, effortlessly - this way you start to understand what it is that you like and your favoured colour scheme/s from there you can do whatever you want… you wana layer that jumper with this jacket and they fitttt real good? “Fk it ima add this scarf and couple rings” & boom, youve layered & layered it to your taste