I am big into coupons. And I would say for things that last a long time that you will always need buying in bulk is good.
This is what I get at Costco:
Chicken (i clean it, put them in baggies and freeze them)
Hamburger
Sugar Free Jello
Toilet paper
Paper Towels
Orbit Gum
Olive oil
Tuna fish
Chunky peanut butter
Not everything there is in enormous quantity. Plus, I think that not having to go for a emergency toilet paper run is a big bonus.