Are these stocking stuffers for your own immediate family members, or for some wider exchange? I tend to fill my kids' stockings with stuff I would buy them anyway (socks, underwear, soaps, bath bombs, their favorite shampoo, gloves/mittens) and snacks (which, to be fair, I would also buy them anyway, but I get versions of things that are a little bit special, like cocoa bombs instead of plain cocoa powder).
My mom would fill our stockings with stuff she got by couponing or those "free with purchase" things, so it was always random brands of deodorants, lotions, etc.
If its something for a wider exchange, I would look at a thrift store. My family does a white elephant exchange where the only rule is that you can't have bought the item new for the purpose of the exchange. It tends to be a mix of regifts and family heirlooms, but people from out of town have gone to used book stores or given cute knickknacks from thrift stores.