Absolutely. The concept of coming up with something to sell (or resell), setting up a barebones store, doing some test advertising and seeing results in just a few days is timeless. It's even easier today than in the past since creating a good looking ecommerce site is easier than ever with all the store builders and payment services available.

If you've ever seen Tim Ferris's book "The Four-Hour Workweek", he suggests that exact system, except without accepting payment and without having the product available yet, so that if people do try to order from you, you've validated that there's a product-market fit before investing time and money into an elaborate website, stocking inventory, etc.