My son does basically the same thing, but sells them through eBay, he specializes in high-quality men's clothing. Does much of his shopping at Goodwills and Savers located in the suburbs, finds high-end stuff that's been donated that the staff doesn't realize is high-end, buys it at thrift store prices, takes professional-looking pictures, and sells it from his eBay store. He makes good money on it, a side income equal to about half of his day job.
Very proud of him, he's way more of an entrepreneur than I've ever been.