Most of us are daunted when we come here, expecting the supermarkets to be just like in the US. When I first came to the area, 9 years ago, there were but two older supermarkets, Calimax and the Commercial. Commercial has added a newer, bigger store. WalMart descended about 3 years ago with a superstore which includes food. Coupons are not used here, so there is not a frenzy of marketing for these items. Calimax does offer a savers card to track your purchases. Every item has two prices, one with the card and one without. It is common to give a small tip. The same goes for the baggers of your groceries. It is easy to come out with the same amount of groceries one would purchase in the states for about half the price. California being one of the highest price places I have ever lived for food, this seems like a big bonus.
The first thing I noticed in all of them were the bakeries, located close to the entrance. They are self serve. One takes a pizza pan, a pair of tongs, and starts selecting from mostly strange looking pastries. The only ones I was familiar with were the Mexican wedding cakes. Big puffs of what look like cookies with sprinkled sugar, in different colors and sizes. Other cookies and muffins in different looking textures and colors from what we are used to up north. Since it seems prudent to try new things in a new country, I would select about 8 and take them home to try. My favorites turned out to be pastries shaped like butterflies, coated with honey and baked until rather brown. Almost everything comes with sprinkled sugar it seems. The sugar is mostly on the outside, as many pastries are not very sweet, rather heavy in texture, without a lot of the flavors like lemon or almond we are used to having. The cakes tend to be more flavorful and moist, so I would recommend sticking to them for your sweets. The breads are good. Quite reasonably priced, about thirty cents for a roll about five inches longbaked several times a day. Some shoppers load up their pizza pans with about twenty or thirty of these right after they come out of the ovens.
Produce is cheaper here than in the states, as are many grocery items like meats, cheeses, fish and the like. Do not expect 3 to 4 aisles of prepared frozen food. Or as large an array of different items as you might expect. Most food down here is cooked from scratch. You can purchase a frozen pizza, but the quality is not very good. Tuesdays are the value days at the Commercials and WalMart, with loss leaders like 10 grapefruit for a dollar. These days can be crowded so prepare yourself for that. Overflowing displays of produce, select your own cuts of meat from a refrigerated cart.
You will see more produce indigenous to Mexico, like papayas, plantains, and mangoes. The Mexicans use a lot of plum tomatoes and different chili peppers. Dried peppers are also found in the produce department. These are quite flavorful and excellent with beans, pozole, pots of chili. Some of the best salsas I have had used dried chipotle peppers which gives them a depth of flavor. Cilantro and parsley abound, but not basil or other specialty herbs not commonly grown here. Canned tomatoes are not a common item here, but the Mexican tomatoes are often fresh from local fields and smell like tomatoes are supposed to smell.
You might wonder about knowing Spanish. A little bit certainly does not hurt, but pointing at pork chops and showing four fingers works quite well. Pounds are not used, kilos are. A kilo is about two pounds. If you want a half kilo of turkey ham, you ask for media kilo. The cost for this approximate pound of turkey ham is three dollars. The cuts of meats are different. Pork chops are often about a half inch. Plenty of ground beef and good. Beef is sliced into smallish slices and used mostly for carne asada. The taco stands use this most of the time. It is not aged or marbled, and probably grass fed beef. The pork is delicious and also of good value. Chicken is wonderfully cheap if you like leg and thigh pieces, generally around sixty cents a pound. It mostly comes frozen.
Most of the cereals will look different. One of the items I like a lot in the cereal aisle is the boxed milk. I first saw boxed milk in France years ago. It is so handy to use and lasts a lot longer than the milk in the dairy case. The baking aisle will not have everything you are used to see either. Less mixes. More kinds of flour for tortillas. Hard pressed to find yeast or baking powder in less than gigantic sizes. Chocolate chips maybe, but not butterscotch or the other myriad flavors for baking.
The cleaning aisles will not have 30 different kinds of laundry soap which I find refreshing. Some of the specialty items like hard water spot remover are not to be had, either. Pretty basic stuff like bleaches, floor cleaning solutions, dish soaps, and ammonia.
Some people prefer the taste of certain American items like butter and wait until they cross the border to purchase them. Many complain about the lack of flavor in the beef, though the chicken has more flavor. It all takes some getting used to. Experiment a bit, try new items when you shop and compare for yourself. You will find shopping for food in Mexico a pleasure if you go in with an open mind.