A produce and meat market, the Mercado Municipal (also known as the Mercado Público, 6:30 A.M.–6 P.M. daily), is on the northeast corner of the plaza. Note that there are two entrances, one on the south side and one on the east side of the building. It’s worth exploring the whole complex to see who’s got the best stuff that day.
There are several supermarkets within a couple of blocks of the plaza. Besides groceries, Supercentro El Mandarín, (Avenida Central at the Calle 2a Sur) carries a range of toiletries, hardware, and other dry goods. The 24-hour Supermercado Romero, behind the post office, has a bakery and pharmacy. They also sell used books in English.
Deli Barú (8 a.m.–8 p.m. daily) offers a modest selection of imported cheese, chocolate, and other goodies that are normally hard to find up here.