Since you have paid the price of admission ($55 a year for Costco and $45 for Sam's Club), it seems logical to think that the more often you take advantage of it, the more you'll save. Still, there are traps to avoid. Even though these clubs have good prices on most items, they are not the cheapest choice for everything they sell.
And, of course, it goes without saying that you're not saving money if you buy something you don't actually need. Your warehouse club may have a great price on wetsuits, but they're not a good value for you if you don't swim and dislike the ocean.
Here are some items you should generally avoid buying from Sam's Club or Costco.
One of the ways warehouse clubs keep costs down is by selling items in large quantities. That's fine for foods with long shelf lives, or for items a family consumes in large quantities, but it's probably not a good idea with perishables. Yes, you can save money per ounce buying a drum of mayonnaise, but unless you're having a party, will you be able to use it all before it goes bad?
When buying anything perishable at Costco or Sam's Club, check the expiration date and do some honest math. And remember that it's not really saving money if you use the item faster than you need to simply so it won't go bad. This applies not only to foods, but items like sunscreen, which can have surprisingly short shelf lives.
Both warehouse clubs offer a small selection of books marked down between 15% and 25%. Generally, that still leaves the prices higher than what you would pay on Amazon. In a broad sense, physical books are now a sucker deal no matter where you buy them. E-books make the most sense price-wise, but if you insist on having something physical to read, online prices tend to start at right around free (plus reasonable shipping costs) for many, if not most, books.
When you see your favorite name brand on the racks at Costco or Sam's Club, it may be tempting to scoop it up, but there are risks, as CouponCabin.com President Jackie Warrick told Today.com.
"Most famous designers make less expensive summer lines just for warehouse clubs and outlet stores -- and these lines may be lower quality," she said. "So if you want long-lasting, well-made clothing by top designers, shop elsewhere."
Aside from the normal issues regarding expiration dates and quantities, milk is not something you should buy at a warehouse club: It's cheaper at the supermarket, CreditDonkey.com's Lauren Ward told Kiplinger's. The research analyst said that a gallon of regular milk can cost $0.50 to $0.60 less at a normal grocery store.
Costco and Sam's Club both sell mattresses, but neither offers much opportunity to try them out. Instead, the mattresses are simply stacked in rows. Comparison shopping is made even harder by the mattress companies themselves, because model numbers with only slight variations can be very different products. That means that the mattress you saw somewhere for more money may or may not be the same on which you see on sale at your warehouse club.
The prospect of an uncomfortable bed is simply not a risk worth taking, even when the price seems right.
It's a bit surprising that canned goods are on this list, because they seem like something that would be a value at a warehouse club. But TheGroceryGame.com CEO Teri Gault told Kiplinger that the best place to buy canned items is still at supermarkets -- when they're on sale. You can expect to pay 20% to 40% less per unit than you would at Sam's Club or Costco. The savings expert also noted that your savings can be even higher if you buy store brands when they are on sale.
Daniel Kline has no position in any stocks mentioned. He has absolutely purchased things he does not need because the price was right. The Motley Fool owns shares of and recommends Amazon.com and Costco Wholesale. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.