My son and his girlfriend have been buying clothes at thrift stores and selling on PoshMark. According to him they’ve made a couple hundred $ although they started with some of her mother’s clothes that she gave them to sell. He says they go to thrift stores and if he sees something he thinks will sell he asks his girlfriend and she says buy or not. She has good fashion sense and they focus on teen clothes. He recently sold a t-shirt that I’d bought him in a bag sale ($20 for all you can stuff in a bag) from a local company with its own brand. He’d never worn it. And I paid for it so it was all profit for them!