For many (or ahem, most of us who don’t have ginormous net worths), owning a designer bag can feel like an unattainable luxury—especially when the price tag looks like the price of rent…and then some.

The no-frills Trader Joe’s mini tote bags are $2.99 and smaller than most traditional canvas shopping bags. Still, whenever they hit stores, they cause a buying frenzy. This week was no exception, ...