for those attending random street parties and blocos, the best option for shopping is definitely the entire shopping district of saara - the neighborhood has literally hundreds of shops offering an endless supply of carnival accessories, at truly low prices. 

saara, the sociedade de amigos das adjacências da rua da alfândega, maintains a webpage on this link, and can be contacted via this email - additionally, this parallel webpage, also offers interesting information of the market, visible on this google map.

within saara, and in business since 1915, casa turuna is one of the best options when looking for costumes of all types, for street parties or bailes - located on avenida passos 125, centro, casa turuna can be contacted via phone at 21 2509.3908, via email here, or via the store's website on this link.

carnival bailes usually require fairly elaborate costumes - these have to be purchased or rented in advance, and from specialized stores.