Should You Buy All of Your Groceries at Costco?

Before I had kids, Costco was a store I visited about once a month. But now that I have school-aged children, Costco is a store I shop at pretty much every week. That's because buying a lot of my grocery staples in bulk allows me to save money.

But while I can't imagine how much I'd spend on food if it weren't for Costco, I also know that I can't make it my sole destination for grocery purchases. And you're likely to land in the same boat.

Why Costco alone doesn't cut it

Costco's bulk prices are often considerably less expensive than those offered at my local supermarket. Case in point: Right now, the cost of five dozen eggs at Costco is $14.03 for same-day delivery, or $0.23 per egg. At the store, the cost is even less, since Costco charges more for same-day delivery items ordered online. So in reality, it's probably more fair to put the cost at $0.20 per egg or less.

Meanwhile, at my local supermarket, right now, a dozen eggs is $3.29, or more than $0.27 an egg. So clearly, there's savings to be reaped buying eggs at Costco. And because my family eats a lot of eggs, and I bake often, buying 60 eggs at a time is not a risk for us. We're likely to go through that many before they go bad.

That said, there are many grocery items my family consumes that we do not need to buy in bulk. And chances are, you're in the same boat. So for that reason alone, it's probably not a good idea to plan to do all of your grocery shopping at Costco.

Similarly, while Costco does offer a wide variety of grocery items, I have to admit that the selection at my go-to supermarket is even larger. In fact, there are certain brands my kids prefer that Costco just doesn't carry -- or in some cases, it doesn't carry the varieties we want.

My family is big on Chobani Greek yogurt, for example, which comes in dozens of flavors. Costco carries this brand, but usually only has a few flavors to choose from. Usually, those aren't the flavors my kids prefer. And it doesn't make sense for me to pay less for yogurt that my children won't eat. In that case, I'm not saving money -- I'm wasting it.

Your supermarket might also have a better deal

Another reason not to buy all of your groceries at Costco? Supermarkets tend to put different items on sale on a rotating basis. But in many cases, you'll pay less at your regular grocery store than at Costco when there's a sale going on.

For example, Costco has a seven-count of Barilla pasta boxes available for $11.10 online. Again, to be fair, let's shave a little off of that total because that seven-pack is going to be cheaper at the store. But even if Costco's price is $8, which would put the per-box cost at $1.14, my supermarket often puts this brand on sale for $0.99 or $1.09. That doesn't happen every week, but it happens often enough that I can get discounted pasta when I need to.

Buying groceries at Costco often makes financial sense when you have a family to feed. But you probably shouldn't expect to do all of your grocery shopping at Costco. Doing so might mean wasting money and limiting yourself to a narrower selection of products, not to mention missing out on cheaper prices elsewhere.