Craigslist, FB Marketplace, Ebay.
In my area there's just a random dude who works as an "electronics recycler" - he buys them off of MSPs in bulk and sells off rebundled PCs. So he just keeps a huge stack of Thinkpads, Latitudes, Probooks, and MacBooks all for about $200-$400.
Nearly every metro area I've lived in has had "a guy" or two who does something similar.