That's exactly right! That is the purpose of those magical objects in the world.
If a commoner has the money, and they have the acumen and access to invest in such resources, they may just do that. But if they don't have the money, or have other financial obligations or money sinks (family, debts, setbacks, drinking, gambling, or other entertainment), it's a moo point. It's outside of their reach, or it they just don't see the value compared to anything else they think they need their money for.
Commoner doesn't mean pauper. Unskilled laborers live at the ragged edge, but skilled workers earn 2gp/day, so the 50gp items are 1 month wages. They only need 1gp/day to live, so if they save 2-3 months they can afford these things, which save them more money in the long run, meaning they can buy even more of them over time.
What is a skilled worker? Well, obviously crafters (smiths, woodworkers, jewelers, alchemists, herbalists, brewers, distillers) and "paper pushers" (cartographers, calligraphers) but also the "common" artisans, like cooks, cobblers, carpenters, masons, painters and potters.
This isn't "the 1%", it's more like 20%, where each skilled worker has a couple unskilled helpers (dish washers, fire stokers, vegetable peelers). Meaning the unskilled likely work part of the time in the light from Continual Flame, near a chef who has a Heward's Spice Pouch, or a calligrapher/cartographer with an Illuminator's Tattoo, or minstrals with Instruments of Illusion or Wands of Conducting.
It's really easy for a Player to know the "rules" of a world and whiteroom metagame it. It's another when the table acknowledges NPCs don't have the same "system mastery".
The "system mastery" here is basic economics. Humans have established a solid grip on that for like 4,000 years. (The Ur Compaint Letter :
Complaint tablet to Ea-nāṣir - Wikipedia) Banking and usury has been around for a loooong time.
Also commoners have to be careful if they have something small and valuable that unscrupulous folk may covet. It could be quite easy for all that value to disappear because they are an easy target/mark with a big payout.
Again....1 month's skilled wages. It's like stealing an 80" TV or a MacBook Pro from a lawyer's house. It doesn't break them, but it makes them mad. Possibly mad enough to offer a reward/bounty.
Rich-people-justice is also "system mastery" that humans figured out several thousand years ago.