The cheapest way to get a meal is to eat at a "hotely" or at market places. Simple meals that include a plate of rice, laoka malagasy for side dish accompanying rice like chicken, beans or pork, and rice water often are about 2000 Ariary about 1 dollar but could even be as low as 500 Ariary. For 200 ariary extra you can get a small glass of homemade yogurt. 'Compose' is a small salad that often includes potato salad and some other vegetables, often available for 300 to 600 Ariary. The same is also available on a baguette. Soups in various kinds, often including pasta are also very popular.
Bananas hundreds of varieties and rice cakes Malagasy 'bread' are staple 'street food' and available everywhere. Coffee is very good, usually hand-made by the cup and served very sweet with condensed milk.Steak-frites is available in restaurants in the larger towns.
Supermarkets - In Tana there is a supermarket chain called Jumbo Score. This Western style supermarket is well stocked, but the expensive prices reflect the need to import just about everything. There are many Casino a French Supermarket branded goods but also some more local produce veg, spices etc, far cheaper from any the street markets. Shoprite is a slightly cheaper alternative but usually a smaller selection of stock items.