I'm a bachelor, but I've gotten what I consider to be solid savings on things I buy.
Some stuff I can remember I've purchased since last fall:
4 sets of organic cotton Cal king bed sheets/pillow cases @ $25 each. Good quality. At least half the cost as online.
2 Snap-On LED portable work lights $25 instead of $44 online.
An LED ceiling fixture light for $27 on Costco sale. Anything comparable is $100+
Non-perishable can foods, cereal, protein drink, etc. much less than even discount grocery stores.
Fuel is .20 gallon less than anywhere else. I save $5 on every fill up weekly.
Over the counter meds, personals, toilet paper, misc. plenty cheaper.
Occasionally there's the need to get some large quantity of something and it comes in handy.
There's something for most people there. I'd be surprised if someone couldn't get value by shopping at Costco. That being said, it's just an option. It's good to have options.
Sent from my iPhone 6 Plus while driving 70mph