ebay!! depop, poshmark, mercari...whatever reselling site u want..very good for old band shirts and that sort of thing just set the "condition" filter to pre-owned or vintage otherwise ur searches will be clogged with knockoffs
hot topic is only good for overpriced cheap shit, id reccomend thrift stores, most hot topic & spencers merch is low quality anyways so its always a waste of money. also def consider diy-ing some stuff!