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The Worst Costco Shopping Mistakes You Should Never Make

Avoid these to save money, time, and space in your pantry!

Nothing can stop you when you have a Costco membership in your hands—not even the estimated 4,000 products in each warehouse. Whether you need a handful of organic tomatoes or toilet paper to last for months, your purchase power seems limitless.

When you first start shopping at Costco, that feeling of power exhilarates you into shopping at a frenetic pace. But as with many other skills, it takes some time and finesse to master the art of shopping at this big-box retailer. And if you're not careful, there are a few Costco shopping mistakes that you can make.

You're probably asking if it's even possible to make mistakes shopping in a store that's as clear-cut and laid out as Costco (even if each store is slightly different). This line of thinking can cause overspending, but if you know what to look out for, you can save money and time on every trip. Whether you're new to shopping at this megastore or just want to sharpen your skills, never make these mistakes that constantly trip up members.


Overpaying for a membership

Costco membership

Selecting which membership level matches your spending goals may seem like it shouldn't involve too much strategy, but you can miss out on certain benefits if you haven't done your homework. While one may assume that a standard Gold Star level membership suits your needs, those who love to buy in bulk or shop for a big family should begin with an Executive membership to really start raking in the savings. There's also a Business membership, which allows for product resales but isn't great for individuals or families. Identifying how often you plan to shop and who you're buying for will help you determine which route to take.


Shopping on Sundays

Photo by DANIEL SLIM/AFP/ Getty Images

Busy shopping days can make heads spin, and if you get overwhelmed by crowds, fighting other shoppers feels like you're walking into your worst nightmare. Statistically, Sundays are the busiest shopping days. Instead, opt to shop between 3 to 5 p.m. on weekdays because these time slots rank as some of the slowest. Plus, less pressure from fighting crowds means you can relax and take in the whole experience.


Buying the wrong items in bulk

Costco bakery

Knowing what you need lies at the heart of saving money and optimizing your Costco run. If you stock up on items that you don't use very often simply because there's a deal, they may expire on your shelf before you even have a chance to crack them open. Alternatively, these items can tempt you in all of the wrong ways. Buying a massive tub of jelly beans may seem like a good call at the time, but unnecessary purchases mean you spend more on items that you probably don't need.


Assuming Kirkland brand is always the best deal

Costco wine

When it comes to quality, Kirkland brand products often beat out name-brand products. In fact, Kirkland products sometimes are the brand-name product repackaged to be sold at Costco. While this brand offers a solid bargain, don't assume that it's always marked at the lowest price. Always compare the generic product to its brand name equivalent, and check their prices against one another. Kirkland offers up some great deals, but don't let your guard down. Otherwise, you might lose out on a deal!


Shopping on an empty stomach

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Shopping on an empty stomach is a bad idea in most scenarios, but disciplined shopping gets even harder if you're tempted by wall-to-wall food. As you likely already know from firsthand experience, shopping while hungry can lead to some wild impulse purchases. Take the time to ground yourself by grabbing a snack at the food court before you hit the aisles. That will help you steer clear of temptation once you reach the bakery section.


Not using the health services

Costco pharmacy

Between discounted health insurance for members, the lowest generic medicine prices, and optometry services, Costco delivers when it comes to supplying basic medical care for its patrons. Going to your local clinic or pharmacy may feel unnecessary once you become aware of all of the health care savings that you can rack up. The warehouse is known for its deals on food and consumer goods, but don't count out its medical services—or you risk letting your membership go to waste.


Comparing Costco electronics

Costco electronics
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One of the most magical aspects of Costco is the fact that you can buy almost anything you ever wanted, including remarkable deals on home electronics. While you can get fixed warranties and support built into the price of this tech, don't assume every computer or TV has the lowest price tag.

Many of the models that Costco carries are manufactured to be sold at warehouse stores and thus lack all of the features you might find at a specialty retailer. Even if the TV is the model that you want, take a close look and make sure it comes with everything you expect.


Not upgrading your membership

Costco membership

After some time, you start to realize what your membership can and can't do. It might be a lot of fun to take advantage of the daily savings, but if you become a shopaholic and really love visiting Costco, consider spending the extra money to upgrade your membership and increase your savings. If you don't visit that often, it might not make sense to spend more. But if you would see savings in the long run by switching things up, take the dive and upgrade to that Executive membership.


Forget to consider shelf life

Costco produce
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Purchasing mass quantities of food may seem like a no-brainer. When you spend so much of your week on the go, the thought of consolidating a grocery run to one big trip can be tempting. If you choose to shop this way, consider the expiration dates on all of the food items that you purchase. The only thing worse than realizing that you can't make the meal you planned after an ingredient goes bad is realizing that you ultimately lost money.


Skip bulk purchases if you're single

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If you currently live on your own and don't entertain guests very often, you might assume that you don't need that crate of paper towels or frozen dumplings. Costco's bulk savings can apply to anyone in any life situation. Stocking up on non-perishable essentials saves you multiple shopping trips and gas money. Costco works for everyone—you just need to figure out which products to buy in bulk to make your life easier.


Only buying items ending in .99 and .98

Costco price
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You've probably seen a bunch of seemingly random prices at Costco that end in a variety of cents. While this pricing system seems spontaneously generated, don't be fooled—it's actually a secret code for shoppers. If the price ends in .99 or .98, it indicates a regular retail price that won't score you any great savings. If the price ends in .89, .79, .69, .59, .49, .39, .29, .19, or .09, it indicates that the item comes from a manufacturer's deal and can be sold at a cheaper price than other retailers. For maximum savings, look for products ending in .97. These items must be sold at all costs and may even disappear from shelves if an asterisk appears in the corner of the price tag.


Forgetting to fill your tank

Costco gas
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The savings don't end once you leave the store. Many of us forget about Costco's auto service station, which features some of the cheapest gas around. If you have already pulled up to the store and need to fill your tank, you often can't beat these prices. If you have to drive a distance just to gas up or fight a massive line of cars to reach the pump, the expedition to fill up might not be worth it. As long as you visit the store at a calmer time, don't pass up this massive value.


Shopping without a list


Shopping with a list always helps us stay on task and avoid making impulse purchases. Such lists are even more valuable when you're navigating the aisles of Costco, a store designed to make you get lost and spend money on things that you probably don't need. When you need to stick to a strict budget and timetable, always draw up a list of items that you need in order to streamline your trip and keep your wallet happy.

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Erich Barganier
Erich Barganier is a health and food writer. Read more about Erich