What country are you in? That info is kinda crucial if you want to avoid high shipping costs and possibly import taxes.

I highly, highly recommend checking out thrift stores since a lot of my decora clothes come from lucky finds. If your local stores suck or they're not in walking distance, mercari jp is a great place to get second hand peices of big decora brands like 6%dokidoki and ACDC RAG when shipping is a little pricey or you've been wanting a retired set piece. Etsy is also a great option, I get a lot of accessories from there. My current fave shop is ConfettiCarousel and TheyCalledHimAngel. I definitely recommend saving up to get a coord from ACDC, since they're prices are sweet for the quality. You can pretty much find protentional decora clothes everywhere, right now I'm working on turning a colorblock tutu into a glittery pompom skirt. Aliexpress also stokes bulk beads and decoden supplies, along with party favors to turn into jewlery.