if you are actually cooking items (vs. getting prepared stuff to heat) you might want to consider taking spices along with you. these are the single most expensive item (by unit price) that we've dealt with. if flying we pack them in our checked luggage-and what I've found to be the easiest way to go is to kind of plan out on what I'm making, premeasure the amount of spices into ziplock bags (sharpie label them w/name of spice and measurement)-then put all the little ziplocks into a larger ziplock. it's one thing to buy a small container of salt and pepper, another to have to buy multiple spices that can run $8 or more dollars for the smallest available container.
you can also always go online and take a peek at the grocery ads for your arrival period (most stores seem to have websites w/ads these days). you might find that you can print off some store specific coupons OR if they have a loyalty club go ahead and join it so that you get the 'club' prices and can 'clip' the coupons on-line so they are already loaded onto your club account when you shop.