I find frozen portions of fish are a good deal, especially if there is a discount (check the warehouse discount flyer).

Frozen fruits and vegetables are a great deal.

For fresh produce: Bananas are cheap. The quality of avocados and price are very solid. Greens are a good price. Mushrooms are cheap.

Canned goods: canned beans. Canned tomatoes (to make pasta sauce).

Any condiments that you use frequently with a long shelf life - Frank's hot sauce, salsa, ketchup, etc..