Costco is not going to be a one-stop shopping experience for you Gibor. They do have a lot of good quality and well-priced items, but they won't sell a lot of the specialty items you describe. You also have to be okay with buying a lot of it at once. Meat it usually sold in 6 or 7 pound containers (like 9 chicken breasts, 9 large sausages), which for me means individually packaging and freezing. Their sausages are great, but not obviously not kosher if that is important.
I find buying giant condiment containers (like ketchup, mustard, etc.) to be a waste of fridge space.
Given your food budget, it sounds like you will get value out of a membership.