Costco's baby spinach costs about $0.25 per ounce, about a third of the price at Wal-Mart. iStockPhoto
Not only did Consumer Reports find that the bacon sold under Costco's store brand, Kirkland Signature, tastes better than most other brands, it's also about $1.50 cheaper per pound than the competition. iStockPhoto
Top-shelf booze is usually a lot cheaper at Costco than the liquor store, and in some states you don't even need a membership to purchase it. Just a couple reasons why it's so insanely popular! Yelp/ Ryan G.
Butter freezes very well (like these recipes), so don't be afraid to stock up on bulk butter at Costco. The per-pound price is a lot cheaper than at the supermarket. iStockPhoto
If you're okay with buying whole cases of canned goods, when the math shakes out, the individual cans in those packs are a lot cheaper than you'll find at the supermarket. And don't forget, you can turn canned foods into lots of quick and easy dinners! ChuckSchugPhotography
Everything from gourmet artisanal cheese to blocks of part-skim mozzarella is cheaper, ounce for ounce, at Costco than at the supermarket. Just make sure you're going to use it before it expires; there's always a reason to eat more cheese! iStockPhoto
Two big bottles of cooking spray (which happens to have plenty of household uses besides the obvious), enough to last you a year, will cost you less than five bucks. Shutterstock
Extra Virgin Olive Oil
The EVOO at Costco is both cheaper and better tasting than the mass-market stuff you'll find at your grocery store. iStockPhoto
Kirkland Signature introduced their own hazelnut spread last year, and the ingredients (and flavor) are essentially identical to Nutella. Costco's prices, however, are much less expensive than Nutella: $7.99 for two full kilograms of the stuff, or $9.99 online, compared to $13.92 for slightly less Nutella at Walmart. Costco
Herbs and Spices
Ounce for ounce, the bottled herbs and spices you find at Costco are much cheaper than at the supermarket. They tend to be sold in bulk, however, so make sure you're going to use them up within a couple years so they don't get stale. iStockPhoto
Hot Dog and Soda
The food sold at the Costco food court is always a pretty amazing value, but nothing beats the hot dog/soda combo. You'll receive a jumbo hot dog or Polish sausage with your choice of toppings and a 20-ounce soda for just $1.50, a price that hasn't gone up in more than 30 years. It's an insane deal. Yelp/ Harvey C.
If you're tired of shelling out for 100 percent pure maple syrup at the supermarket, Costco sells the cheapest maple syrup around. iStockPhoto
Kirkland's mayonnaise is basically identical to Hellmann's, but it costs half as much. iStockPhoto
Pure Vanilla Extract
The pure vanilla extract at Costco costs less than most supermarkets are charging for the imitation stuff. iStockPhoto
A package of 60 sticks of string cheese will cost just $9.99, or less than 17 cents per stick. That's a huge savings from supermarket prices. It's okay to bite it! Shutterstock
Vanilla Ice Cream
Vanilla ice cream is another example of a Kirkland product that tastes better than the competition (according to Consumer Reports) and is also less expensive. iStockPhoto
Costco tends to have some pretty decent bottles available in the six-to-nine-dollar range; they're of a much higher quality than the cheapest bottles at your local wine shop, and it's a great way to sample wine from some surprising places. Yelp/ Corine M.
The three-pound (minimum) rotisserie chicken at Costco is always $4.99 across the board, which makes it the cheapest you'll find anywhere. The closest competitor, Wal-Mart, sells theirs for a dollar more, and the chickens they use are smaller! Costco would rake in 30 to 40 million more dollars annually if they raised the price by a buck -- just one of many things we bet you didn't know about this famed bird.
More From The Daily Meal:
10 Things You Should Never Buy at Costco (and Where to Buy Them Instead)
Ways You're Wasting Money at the Supermarket
18 Costco Items Every Parent Should Know About
21 Great Dishes You Can Make With Supermarket Rotisserie Chicken
Ways to Stretch Your Food Dollar at Costco, BJ's, and Sam's Club Yelp/ Angel H.