We've been Costco members for almost 7 years. Joined in Dec 2006

I'm a huge fan. We buy pretty much anything we can there.
They do have a ton of gf and df food items. Ours carries almond flour, coconut oil, flax meal, quinoa, coconut milk, almond milk and tons of other foods that fit our special diet nicely and for less money
The meat is better quality and cheaper, imo. Organic beef is way cheaper than organic beef elsewhere.
We buy eggs, yogurt, almost all produce, coffee, nuts, diapers, toilet paper, paper towels, tissues, etc.
We don't buy a ton of things like crackers, granola bars, chips or soda. I'm not sure how those things compare price-wise. If I buy a 'junk' food, I don't want Costco size quantities
So, we buy a lot there, eat it all and save a ton of money. But we are a family of 6 and we rarely eat out. If we had less people and didn't eat at home as much as we do, I'm not sure I'd feel it was worthwhile.
We also do the Executive membership. I *do* routinely spend $400 per cart
