Be careful when shopping online. The prices vary enormously. I have taken as one example: Fancy Feast Gourmet Cat Food, 3-Flavor Seafood Variety Pack, 3-Ounce Cans. There are many online retailers that sell this product. The prices range from, $10 to $27.99! These are excluding delivery.
Buying online can save big even when you include delivery because you get good discounts. If you buy in bulk that more than covers the delivery charges. On the featured product you get free shipping on orders over $25.
One of the best discounts can be had at Amazon. See the advert on this page. When you include free shipping this is the best deal. The saving product price is 39% on RRP.