Costco Mistakes That Could Cost You

Costco is a mecca for bargain-minded shoppers. Sure, you have to buy an annual membership to get in the door — but in return, you get access to a world of high-quality goods at great prices, all backed by a generous return policy. Whether you need a household appliance, a set of tires, seasonal clothing, fresh produce, or the biggest containers of Lysol wipes you've ever seen, you can find almost any type of product at Costco.

But despite its legendary reputation for great prices, there are lots of common Costco mistakes that could end up costing you money. Make sure you're not doing any of the following. (Not a Costco member? You can apply here.) And if you know of Costco mistakes that we haven't listed, let us know what they are in the comments.

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You almost always need a membership to shop at Costco — but there's one handy loophole. These favorite tips come from Jen Coleman and Laura Wiertzema of Costco Does It Again, who note that "You can always Instacart Costco, even without a membership!"

The prices won't be as good through Instacart as when you shop in person, but if you crave a serious Costco bargain only a few times a year and aren't buying big-ticket items, you can order from Costco via Instacart and get that fix without leaving the house.

Related: How Non-Members Can Shop at Costco

Let's say you want to visit Costco in person, since prices are best in the warehouse and it's fun to explore and see what new items have arrived. But don't do your run on a Sunday if you can help it: As Coleman and Wiertzema explain, the crowds are just too crazy.

If there's a big payday in your area — say, if lots of people tend to collect paychecks on Fridays or the first of the month — you can expect Costco to be as packed as it ever gets on a Sunday. Save yourself some trouble and stay home on those days too. Part of the beauty of bulk shopping is that you can usually afford to wait a while before the next trip.

Related: The Big Differences Between Costco and Costco.com

If you're a frequent shopper, a basic Costco membership pays for itself pretty quickly through all the savings you'll reap. But as Matt, editor of Costco Insider, points out, spending $250 a month or more at Costco means leaving money on the table if you don't upgrade to an executive membership. It comes with an automatic 2% cashback bonus on everything you buy at Costco, as well as discounts on insurance and mortgages.

Related: Don't Miss These Perks of Costco and Sam's Club Membership

If you buy an executive membership but don't end up shopping enough to make it pay off, no problem: Matt at Costco Insider explains that Costco will refund the difference between that membership and a basic membership.

That's not an automatic perk, though — you'll have to ask, and it applies only if your 2% refund is less than the cost of the membership upgrade.

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Skipping the Costco app won't necessarily cost you money, but it could cost you time if you forget to bring your Costco card on your next shopping trip. As Coleman and Wiertzema explain, you can use the app to get into the warehouse — and more importantly, check out with your purchases — even if you don't have your card.

No app? No problem. Go to the membership counter, show ID, and they can issue you a temporary paper membership pass for shopping that day.

Related: I Shopped at Costco for the First Time and This Is What I Learned

It's easy to get drawn in by Costco's prices, but sometimes the giant quantities really are more than you can reasonably use. A set of dishes for 10 is a great deal — but do you need that many bowls? If not, you could save money by shopping somewhere else and buying the few items you do need a la carte.

Related: Types of People Who Shouldn't Shop at Costco

Shopping on an empty stomach is bad because you feel like you need all the food. It's even more of a problem in Costco, land of the free samples designed to provoke you into impulse buys. When everything around you is a bargain, it's even harder to resist.

Related: Tips for Shopping at Costco If You Live in a Small Home

How do you improve on Costco's already amazing prices? By buying bakery, meat, and deli goods the same way Costco does — by the case. Look for special "by the case" price lists near relevant sections, or ask an employee if case pricing is available on your favorite items.

The obvious downside: You're going to need even more space than usual to store those new Costco purchases.

Related: Costco Brand Products That Shoppers Love

"Items are constantly going on sale," says Matt, editor of Costco Insider. "It can be a lot of hassle trying to get a price adjustment after the fact." If you're a serious Costco-phile, consider subscribing to Costco blogs for a peek at upcoming coupon books and sales so you can shopp around the best prices.

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It's distressingly easy to overbuy at any bulk retailer, as the packages are just plain bigger than what you'll find in regular grocery stores. Heading to the local grocer for two cartons of eggs is very different from bringing home two Costco-sized cartons of eggs. 

"We suggest you look more carefully at the expiration dates and really consider whether you'll get through the whole package before it expires," Matt says.

Related: Recipes to Use Up the Bulk Food You Overbought at Costco

It's hard not to admire the deals on Costco price tags, especially if you manage to catch something on sale. But take another look. "Costco price tags can reveal a lot more than you might realize," Matt says. "Items that end in .97 mean they're on clearance. Items ending in .00 mean they're a manager's markdown. The star/asterisk in the top right corner means there are no more pallets of that item in the store, which is a sign that it's probably not going to be restocked that year."

Related: Surprisingly Expensive Products From Costco

Speaking of watching price tags, pay close attention to Costco's deals on seasonal clothing and equipment. Every once in a while you might find something silly, such as puffy jackets for sale during triple-digit heat in Arizona. But most of the time Costco has great buys on season-specific clothing and recreational gear.

These items tend to sell out very early in the season and may be replenished sporadically if at all — leaving you to pay a much higher price to buy the same thing somewhere else.

Related: Things You Probably Didn't Know About Costco

Costco's in-store deals are great, but don't forget to browse the website. Sometimes you'll get lucky and score online-only deals that have the Costco prices you'd expect but aren't available in the bricks-and-mortar stores.

Bonus: If an item is no longer available in the local Costco warehouse, there's a slim chance you might find it on the website. Don't dally — those last few online items always sell fast.

Related: Beauty Products Worth Buying at Costco

Costco's bulk buys may be large enough to feed a big family, but they're also great deals for singles and small families — as long as you have somewhere to put the extras. Juggling piles of paper towels and toilet paper can be inconvenient, but it's fitting things in the freezer that really becomes a critical issue.If you overbuy, you might find yourself surrounded by suddenly perishable foodstuffs that have nowhere to go.

Related: Costco's Best Buys for Packing Your Freezer

Costco usually offers gift cards or gift certificates for local restaurants and attractions — movie theaters, water parks, and the like. You may also find gift cards for big companies such as Apple, Cold Stone Creamery, and so on.

You don't get to choose the denomination of the gift cards, and they're usually for a pretty sizable price. But if those gift cards are for something you'd buy anyway, they represent significant savings. For example, Costco might sell four $25 restaurant gift cards (a $100 total) for $75 or $80.

Related: Amazing Gift Card Deals From Costco and Sam's Club

Buying car or truck tires can be a giant regular expense. Costco offers reasonable prices for swapping out tires as well free lifetime balancing, rotation, air pressure checks, replacement valve stems, and air pressure checks, so if Costco has the tires you want and is close enough to serve as a service center, jump on the deal. It installs only tires that you buy at the warehouse.

Related: What's the Best Place to Get New Tires?

If you take prescription medications, check out prices through Costco; you might be able to save some money and even sign up for additional discounts through the Costco Member Prescription Program. 

But the pharmacy/clinic corner of your local Costco is good for more than just prescription meds. Many locations also offer free or low-cost screening tests for hearing, diabetes, osteoporosis, and heart health. 

Related: Health Products and Services That Cost Less at Costco

Pretty much any photo-driven items you can buy online, you can order and pick up for competitive pricing right in your Costco warehouse. Yes, that means canvas prints, holiday cards, and wall calendars personalized with your photos — but we're also talking coffee mugs, photo books, and even fleece blankets with your photos on them.

Costco is one of the last refuges of a no-questions-asked return policy (or at least not many questions). If you think there's something wrong with a product, the store will take it back at any time, with only a few exceptions. If you're shopping for big-ticket items, passing up on that kind of guarantee could mean losing a lot of money.

That's why Coleman and Wiertzema love to buy appliances at Costco. "We know that if something goes wrong, they will take care of you," they say.

Related: Store Return Policies for Amazon, Walmart, Best Buy, and More

It's almost impossible to go wrong with most purchases in a Costco warehouse. As John, the blogger behind the site ILoveCostco, affirms, "I have one rule: When in doubt, buy from Costco."

He allows that there are a couple of exceptions — specifically, computer items and designer eyeglass frames. In those cases, he says, there are so many vendors selling the same things online that it's worth taking a while to shop around. "Last 10-plus years of being a Costco shopper, I didn't buy a single computer product from Costco," he admits.

But he adds: "If you're not a savvy shopper and you don't like the hustle? Then just buy from Costco. There are no Costco mistakes."