1. Wine
You can get great wine at Costco, from everyday sippers to special-occasion bottles. All Costco wine is only marked up between 10 and 14%, compared to 25 to 45% at other liquor retailers, according to Fox News.
That means good bargains for just about any label, but their Kirkland Signature brand wines, many of which are made by reputable wineries and white-labeled for Costco, are particularly affordable.
2. Vodka
In my experience, Kirkland Signature liquor can be a little hit or miss, but one line that consistently scores top marks is KS vodka.
One popular theory alleges that Kirkland's vodka is actually Grey Goose, though the more mundane reality is that the two simply share a water source, the Gensac Springs in the Cognac region of France.
Regardless, KS Vodka has outperformed Grey Goose in more than one blind taste test, and it costs half as much as Grey Goose.
3. Diapers
If you've got a newborn, Costco is a budget blessing. Their bulk diapers receive high marks from parents and family publications alike and cost as little as $0.16 per diaper (and that's online, where Costco often charges slightly higher prices than in-store).
The average newborn will need around 2,700 disposable diapers in their first year, at an average cost of $0.20 per diaper, according to Investopedia. In other words, that $108 savings (figuring a $0.04 difference per diaper) should pay for Costco's $60 Gold Star membership itself.
4. Coconut water
If you like to keep coconut water in the fridge – to drink after workouts, for general hydration, or after a night of partying – then KS' line of organic coconut water is a delicious way to keep your shelves stocked.
5. Golf balls
Kirkland's golf balls have been beloved since they debuted in 2016, even receiving high marks from the golf press.
6. Nuts (cashews, almonds, walnuts)
Costco previously carried more name-brand nut products, but it dropped them when their prices rose too much for the company’s liking, according to Fox Business. Instead, Costco started to buy and package its own nuts.
Now, the KS line is a terrific bargain for tree nut lovers: KS' almonds, for instance, cost less than $5 per pound online, while CVS' offerings are about $9 per pound.
7. Allergy medication
Allergy medication isn't cheap, and KS' allergy products are a bargain across the board.
KS' Aller-Tec, for instance, is just $15.49 online for 365 pills, compared to almost $40 for 70 tablets for name-brand Zyrtec. Even CVS' private-label version of the drug is still $34.99 for 120 pills.
8. Coffee, coffee, coffee
If you've got a three- or four-cup-a-day habit, coffee costs can add up. That makes Kirkland Signature's quality-to-price ratio for specialty whole bean blends enormously appealing.
A pair of three-pound bags of premium Sumatran Whole Bean coffee will set you back $46 online, while the equivalent amount of Starbucks' Sumatra Whole Bean would cost about $69 at Walmart.
9. Olive Oil
In a world of sham, overpriced olive oils, Kirkland manages a mean feat: An imported olive oil that actually passes the "extra virgin" test.
At $16.99 for a two-liter jug through Costco's website, you can dress salads and marinate meats in this stuff all summer long.