4 Items You Should Never Buy at Full Price From Costco

Costco has never had wide profit margins on its product. Its average markup -- what Costco charges above the product's cost to cover its overhead -- is about 11%, which is lower than Walmart (24%), Home Depot, (35%), and most supermarkets (30%), according to Business Insider. It's a miracle Costco makes any profit at all. It's even more shocking when you see Costco cut prices for products you actually want, like a new laptop. 

Over my time as a Costco member, I've seen the same discounts on goods. So predictable are its promotions, in fact, it would be silly to buy certain goods at full price. Like these four. 

1. Laptops 

Average savings: $150 to $200 

Costco may not have the widest selection of laptops, but it frequently has the lowest prices on the ones it sells -- even without a discount. Add in a promotion and you could easily save between 10% and 15% off the market price of a new laptop. 

For instance, I've been eyeing a 16-inch Macbook Pro (M2 with 512 GB) for quite some time. Normally, this laptop is priced at $2,449.99, which is $50 cheaper than buying it from Apple. But every now and then, Costco will cut $200 off the listing price, making it $2,249.99. The promotions never last long -- for example, the last one ran between Sept. 17 and 30 -- but they happen frequently enough that I just need to wait to avoid paying full price. 

2. Tires 

Average savings: $50 to $100  

Costco's tire center regularly has promotions when you buy a set of four. Back in the day, these promotions were usually $150 off. But ever since it waived the $19.99 installation fee ($79.96 per set), its promotions have ranged between $50 and $100. My tip: if you know you'll need a tire change within the next four to six months, I'd act on a tire promotion as soon as you see it. If you wait until it's too late -- like, you're basically skating on bald tires -- there may not be a promotion and you might get stuck paying full price. 

3. Mattresses 

Average savings: $150 to $300 

Costco loves to sell mattresses below full price. For instance, during its Labor Day sale, Costco was giving away $200 to $300 Shop Cards with the purchase of certain Tempur-Pedic mattresses. These kinds of discounts aren't rare for the warehouse retailer: Last holiday season, Costco had discounted certain Beautyrest mattresses by $150 to $200. If you're in the market for a mattress, keep your eyes on this year's holiday savings. 

4. Costco memberships 

Average savings: $30 

Finally, new members (and former members who come back after 18 months) can make a rookie mistake by paying full price for a Costco membership. While memberships aren't too expensive to begin with -- $60 annually for a Gold Star and $120 for an Executive -- Costco makes it even cheaper by frequently running promotions. For instance, you can get a $30 Shop Card when you sign up for a new membership with code CJPROMO and enroll in auto-renewal. 

How to stay on top of new Costco deals 

Costco sales can improve your personal finances by cutting prices on things you actually want. To get updated frequently on deals, download the Costco shopping app and enable push notifications. This will ping you when Costco has new deals. The app isn't super advanced (it won't, for instance, ping you when Costco is running a promotion on something you want), but it can keep sales top of mind and perhaps prevent you from buying something at full price.