Wirecutter's affiliate program might make you doubt the legitimacy of Wirecutter's recommendations -- but, in fact, it's quite the opposite. Wirecutter only makes commission when a reader purchases a product from an affiliate retailer and doesn't return the product. Wirecutter, then, has no incentive to promote inferior products -- if they did, they'd make less money and turn away readers.
Antiques, baked goods, catering, gourmet pet food, daycare, massage therapy, nanny service, personal chef, personal shopper, personal trainer, photographer, tutoring, wedding planning, wine consultant. You might create your own brand of homemade pet food and set yourself up to sell it on your own website. Parents and even older post-graduate students are usually very willing to part with dollars if you have the appropriate background to help them or their kids ace that next important test. As for catering, why not deliver homecooked meals from your own kitchen? Who says you have to invest in a commercial setup and do large events for hundreds of guests?
Perhaps most importantly, though, would-be eBay moguls need to specialize. Just throwing junk online won’t work. Sellers need to know what they want to sell and how they’re going to market it to their audiences. Again, competition is fierce, so research, preparation and strategy are critical. (For reference, eBay itself provides an extensive guide to selling on the site.)